Model Rocket Launcher Bluetooth Android

Summary

This post follows the development of Bluetooth model rocket launcher hardware (open source) with an Android phone application. For those interested in already completed designs, there exists projects for wireless model rocket launchers on Instructables, Model Rocket Forum, MakeZine or crowd funded sites such as Indiegogo. To paraphrase David Papp from his 2014 Indiegogo campaign, there is undoubtedly a requirement for model rocketry control and launching to be technologically brought out of the dark ages.

To expedite development of the prototype, the launcher project was based on an existing Cypress Bluetooth Robot design. The hardware component of the design was based on a Cypress BLE module and the Android application was derived from the Robot application. As pictured below, minimal changes were made to the Android Studio app. All credit to Cypress for the original design.

Example of Rocket Launcher Application

Wireless Design Features
The list below details several designs features of the prototype build.

1. Fully isolated igniter. No power rails are connected to the igniter with a view to minimising incorrect ignitions
2. Reverse bias battery protection. Diode protection to prevent false ignitions from incorrectly connected batteries with single FET designs
3. Electronic switching with Smart Switches for igniter control
4. Electronic switches with inbuilt overcurrent protection, voltage and current monitoring
5. Optional monitor to check and or log launch current
6. Optional OLED display for user feedback providing better full sun contrast
7. Option to use a UHF module instead of Bluetooth
8. Option to use a pushbutton for launching and no wireless communications

Schematic
Whilst looking for a Bluetooth module the range of parts was vast. From Microchip to Expresssif with digital to serial interfaces most were fit for purpose. Only after stumbling across the Cypress Robot with BLE App by Alan Hawse, which details most of the steps in building an application with Android Studio, was the Cypress BLE part chosen.

Bluetooth Module
The Cypress BLE module (CY8CKIT-143A) was selected for the launcher. For the PCB design software the schematic and PCB parts were drawn. Below are the schematic connections to the BLE Module. As usual the connections were allocated in conjunction with Cypress' PSoC Creator.

CY8CKIT-143 Rocket Launcher Schematic Connections

To design the PCB footprint for the module, Gerber files were imported into Altium using the technique described in a previous blog. From the Cypress PSoC 4 BLE Module Gerber pack, the PSM.art file was imported as it contained the module circuit board shape and the location of the pads for the two dual row headers. The file was renamed to PSM.cam, an opened in Altium resulting in the capture shown below.

Altium Imported CY8CKIT-143A DXF

No 3D model existed for the CY8CKIT-143A module so to indicate module positioning and sizing, two dual row male headers were placed as shown below.

CY8CKIT-143A PCB Library Part

For interface connections to the CY8CKIT-143A module, several inputs and outputs were added as options.

CY8CKIT-143 Rocket Launcher IO Connections

Decoupling and power supply filtering was implemented with the common ferrite - capacitor design seen on many PSoC development boards. The development module does contain some on-board filtering with ferrites connected to only a single connector (J3) and not the two main connectors (J1, J2).

CY8CKIT-143 Rocket Launcher External Power Supply Rails

Bluetooth Module Power Supply
The Bluetooth module has an operating voltage from 1.9V to 5.0V although for the prototype system the voltage was set to 5.0V. For those interested in power savings, the system voltage could theoretically be reduced to 2.5V; the caveat being the control voltage for the high-side driver which is listed as 2.1V.

CY8CKIT-143 Rocket Launcher 5V Power Supply

Shown above is the switch mode power supply which features the reverse bias protection for the power supply and the igniter high-side drivers.

Igniter Activation
Igniter activation is achieved using a pair of high and low side switches. The design of the circuit would facilitate removal of one of the switches although having a pair was considered the safest solution. Certainly a similar solution could be achieved with a half-bridge or similar device.

Rocket Launcher Igniter Activation Circuit

In terms of resistance in the active devices, the high side switch (VN7040AS) has a typical ON resistance of 40mR and the low side switch (VNL5030S5) typically 30mR. The total resistance of the switches is orders of magnitude lower than the resistance quoted for an Estes Igniter #302301 at 800mR. This should result in the suggested minimum current being met.

Igniter Current Sensing
Current sensing can be achieved using the high side switch, if the measurement is intended for high currents. It should be noted that the current sense ratio drift for the VN7040AS is + 5% for currents at 4.5A or + 30% for currents between 0.01A and 0.03A.

Rocket Launcher Igniter Current Sensing Circuit

An optional dedicated current sensing chip (INA219) was included in the design for higher accuracy current measurements. Even though this device is an older part, circa 2008, the device is well supported, senses the bus voltage from 0-26V, uses an I2C interface and has an accuracy of 0.5% over the operating temperature.

Display (OLED)
An OLED was chosen over an LCD because of the high contrast required in sunlight readable applications. Other factors which were considered include the operating temperature which for an OLED appears a standard -40 to +80C and that no external contrast setting is required for an OLED.

Rocket Launcher OLED (Optional) Circuit

Buzzer and LEDs
To provide audible feedback before activation of the igniter, a buzzer was included. Also shown in the image below were two LEDs, one for the Bluetooth status and the other for general operational status.

Rocket Launcher Buzzer and LED

RF Module
On a prior rocket launcher design, a straightforward 433MHz UHF remote transmitter and receiver module was used for controlling the rocket launch. The same UHF module was retained as an option in the Bluetooth design.

Rocket Launcher RF Module (Optional)

Manual Launch
For those requiring no remote control but the safety of high and low side switches, a manual push button launch switch was added to the design.

Rocket Launcher Manual Launch Push Button (Optional)

Managing Options
A number of options were included in the hardware and to manage these four version resistors were made available to the CY8CKIT-143A module.

Rocket Launcher Option Management

Firmware
For the PSoC microcontroller, the hardware and firmware were developed in unison. This process ensured systems such as the ADC were mapped to the most appropriate pins of the microcontroller.

PSoC Launcher Misc Components

The capture above shows the Bluetooth, I2C (ADC), UART (debug) and OLED components.

PSoC Launcher Timer Components

Below is the ADC component connected to the high side switch. The current sense output of the high side switch is passed through a resistor to provide a scaled voltage representative of the measured current.    

PSoC Launcher ADC Component

Three timers were allocated in the Launcher firmware. The first timer was a system tick timer, second a PWM for the buzzer and lastly a PWM to flash the Bluetooth LED.

PSoC Launcher Inputs and Outputs

In the above capture the remaining inputs and outputs were allocated. These consisted of control and feedback from the high, low side switches, hardware option inputs, UHF module inputs, UART hardware debug output and status LED.

Tick Timer Configuration
A tick 'system' timer was included in the design with a view to controlling the launching process.

PSoC Launcher Tick Timer

Buzzer Timer Configuration
To modulate the buzzer, a 3.9khz PWM was established.

PSoC Buzzer Timer

LED Timer Configuration
To indicate the status of the launcher Bluetooth connection, an LED was driven by a timer using a slow PWM.

PSoC LED Timer

UART Configuration
For debug a UART was configured at 921600, 8, N, 1.

PSoC UART (Debug)

ADC Configuration
The ADC was configured for an unsigned result and an 8 bit resolution. This resulted in a quick sample rate and a step size of around 50mV.

ADC Configuration

Bluetooth Configuration
The setup of the Bluetooth in the Launcher PSoC application closely followed the Cypress Robot project which was covered in the post "How to Create a PSoC BLE App: Lesson 3 Configure the BLE Component". The capture below shows that a custom GATT server was configured.

Launcher BLE General

There were changes made to the Robot profile to suit the launcher. This profile and some of the services were renamed to suit. This service was configured with a field size of uint8.

BLE Launch Service

As shown below a battery service was also added to the BLE for monitoring purposes. This service was configured with a field size of uint16.

BLE Battery Voltage Service

All remaining configuration was unchanged from the original Robot PSoC application.

Software
For testing and to limit the number of changes in Android Studio, the primary user interface (activity page) was updated. Corresponding changes were made in the associated Java files, MainActivity and PSoCCapSenseLedService. Shown below are the changes between the original Cypress BLE101 application and the updated application activity page.

Original Cypress BLE101 Activity Page

Updated Cypress BLE101 Activity Page

Unused features such as the CapSense and LED were removed from the Android Studio application. Provision for the battery voltage was added onto the activity page.

To confirm that the Android Studio application was able to connect with the Cypress BLE module, a straightforward test was made. A compatible phone was loaded with the updated Android Studio application and the BLE module, powered by the MiniProg programme, was loaded with the Cypress BLE application.

Cypress BLE Module MiniProg Powered

A Bluetooth connection was made between the phone and BLE module.

PCB Layout
Before starting the PCB layout, an enclosure was required to house the control printed circuit board (PCB) and battery. An ABS case with a clear cover was available from a local supplier, Jaycar, which comfortably fit the battery.

HB6412 Enclosure - Courtesy Jaycar

With the battery moved toward one end of the enclosure this allowed plenty of room for the Bluetooth Control PCB. The dimensions of the PCB are shown below.

Bluetooth Control PCB Dimensions

Shown in the capture below is the PCB will all components placed onto the workspace. Parts such as the optional display and mounting holes already placed.

Bluetooth Control PCB Parts Placement

The PCB was designed for 4 layers which consisted of two external signal layers and two internal power planes. Shown in the capture below is the routing for the prototype board.

Bluetooth Control PCB Routed

Shown below are top and bottom layer captures of the control PCB loaded with all options.

Bluetooth Control PCB Top 3D

Bluetooth Control PCB Bottom 3D

Power Up Testing
Manufacture of the PCB was performed by Chinese company PCBWay.

Bluetooth Control PCB Top Layer

Bluetooth Control PCB Bottom Layer

For initial testing, the components associated with the 5V power supply and dual outputs were populated. A controlled power-up test was performed on a current limited supply. During this time the 5V switch mode supply was monitored for stability.

Control PCB Populated Power Supply and Drivers

With the on-board power supply operating as expected, the high and low side drivers were tested. The two headers required for the Cypress Bluetooth module were fitted which allowed the control lines for the drivers to be connected to the 5V supply.

Control PCB Populated BLE Headers

The hardware setup used for initial measurements of the high and low drivers under load is shown below.

Control PCB Driver Load Testing Setup

The following table lists two load measurements performed on the drivers.

Load Measurements

Code Testing
As this project was inspired by the Cypress BLE Robot design, the original PSoC application was used as a template. Minor modifications were made to the BLE Callback and a state machine for the launch control. To test the code changes the BLE Module was plugged into the control PCB then the Bluetooth and Status LEDs fitted. These LEDs are indicated by the yellow box in the image below.

Control PCB with Cypress BLE Module Fitted

The red box in the image above indicates the on-board MiniProg programming connection. Linked below is the PSoC Creator 4.2 project used for testing.


OLED Testing
A community submitted PSoC Creator component was used for the OLED. All credit to Thanasis Georgiou for the component.

WS0010 PSoC Creator Component

A Winstar WEH1602 OLED was used for the project.

Winstar WEH1602 OLED

The relevant header was soldered onto the PCB then the OLED fitted.

Powered OLED on Control PCB

To secure the OLED to the main control PCB, four M2.5 x 12mm metal standoffs were used.

OLED 12mm Standoffs

For the messages shown on the OLED, only a few modes were used which included a countdown timer. Brief video of the operation is shown below.

Enclosure
The plastic enclosure was supplied with an internal metal mounting plate which was used as the base the control PCB. Metal standoffs, M3 x 25mm, were required to space the control PCB from the metal mounting plate due to the height of the DIN connector.

Control PCB Mounting Plate

To facilitate access to the DIN connector, one of the metal latches was removed from the enclosure. 

DIN Launch Connector

The control PCB was justified to the right side of the enclosure to ensure that the DIN connector eject button was accessible.

Control PCB Mounted

To secure the battery in place, a steel plate was fashioned then covered in heatshrink. One of the mounting holes for the metal plate was repurposed for securing the battery. A second hole was added to the metal plate with an M4 nut soldered to the rear of  the plate. 

Assembled Launcher

A key-switch was added to the case then the battery wires were added. The image above shows the mock-up of the launcher.

Launch Cable
To connect between the launch controller and the igniter, an IEC mains cable was repurposed. An XLR connector was fitted for the launcher interface and crocodile clips were soldered on the opposite end.

XLR Launch Cable

Field Testing
Field testing was performed with a range of Estes igniters. The clips below show some of the launches performed.

Project Files
Listed below are the schematics, Gerber files, PSoC Creator 4.3 project archive and the Android application. Android source can be supplied.

Launcher Schematics

Launcher Gerber Files

PSoC Creator 4.3 Archive

Android Application 

Final Thoughts
There are a number of updates and additional features to add to the project. Some of these features include monitoring the battery voltage and current during a launch. These will be investigated in a subsequent blog!

Wavedrom for Timing, Documentation and Doxygen

Summary

This post illustrates the benefits of using timing diagram software for debugging and project documentation. Examples of timing software packages used for various purposes include Timing Editor, WaveDrom, Timing Analyser and Waveme. 

The implementation in this blog is presented using the JavaScript tool, WaveDrom integrated with Blogger. All credit to the original developer!

Note than the inline Javascript (Wavedrom images) may not execute or display on mobile browsers. 

WaveDrom Timing Example
To illustrate a known issue with timing, the input and output states of a controller in a previous blog were used. The timing diagram below captures the power up state, states when a button was pressed then released and lastly the effect of a firmware controlled signal for disabling a hardware output. 

The unhandled state was only located after testing however drafting the diagram shows an unhandled state when the firmware controlled signal changes to false. This issue is identified on the timing diagram with the markers a-b and comment 'state'.

For the WaveDrom generated timing diagram shown above, the editor implementation is detailed below.

{signal: 
 [
   {name: 'PSoC Firmware' , wave: '07|.................', node: '....................' },
   {name: 'Control ESTOP' , wave: '05|.............0...', node: '....................' },
   {name: 'ESTOP IN1' , wave: '0.|.5....0....5.....', node: '....................' },
   {name: 'ESTOP IN2' , wave: '0.|.5....0....5.....', node: '....................' },
   {name: 'Contactor'   , wave: '0.|..5....0....5..0.', node: '....................' },
   {name: 'ESTOP LED'   , wave: '0p|...5....n..05....', node: '..................a.b' },
], 
  edge: ['a->b STATE'],
  config:{skin:'default'},
  head: {text: 'ESTOP Controller'}
}

Although the unhandled state was a simple example of timing analysis, it serves to illustrate the benefit of checking logic or drafting timing diagrams.

WaveDrom for Documentation
WaveDrom has an additional feature referred to as Reg which refers to register. This feature can be used for documenting the function of bits in registers. 

As an example of the register feature, the communications packet for a Tracer RN series MPPT was extracted from an older blog. Originally the Tracer protocol document was created (updated) in MS Word then published as a PDF for distribution on the web.

Below is an example Tracer RN command packet taken from the protocol document.

Tracer Documentation in MS Word

At the time of writing, WaveDrom does not support a byte representation with the Register feature, however the bit feature can easily be repurposed to represent bytes. Shown below is the same communications packet structure represented in WaveDrom.


For the register that is displayed above, the WaveDrom editor implementation is shown below.

{reg:
[
  {bits: 2,  name: 'End', attr: ['0x7F'], type: 5},
  {bits: 4,  name: 'CRC', attr: ['CRC16', 'x1041','Bits 13:6'], type: 2},
  {bits: 2,  name: 'Ctrl', attr: ['ON = x01', 'OFF = x00'], type: 4},
  {bits: 2,  name: 'Size', attr: 'x01', type: 4},
  {bits: 2,  name: 'Cmd', attr: 'xAA', type: 4},
  {bits: 2,  name: 'Req/Reply', attr: ['Req x01', 'Rep x00'], type: 4},
  {bits: 12,  name: 'Head', attr: ['xEB x90 xEB x90 xEB x90'], type: 5},
], 
  config:{bits: 26}
}

WaveDrom with Doxygen
WaveDrom diagrams and registers can be displayed in the Doxygen generated output using the Doxygen htmlonly special command. This special command can be used in usual source, header and markdown (.md) files.

WaveDrom in Doxygen

Generating the main page output shown above was achieved using the contents of the markdown file detailed below. Doxygen was tweaked to display a navigation tree.

/** @mainpage Register Example
@htmlonly
<script src="https://wavedrom.com/skins/default.js" type="text/javascript"></script>
<script src="https://wavedrom.com/WaveDrom.js" type="text/javascript"></script>
 <script type="WaveDrom">
 {reg:
[
  {bits: 2,  name: 'End', attr: ['0x7F'], type: 5},
  {bits: 4,  name: 'CRC', attr: ['CRC16', 'x1041','Bits 13:6'], type: 2},
  {bits: 2,  name: 'Ctrl', attr: ['ON = x01', 'OFF = x00'], type: 4},
  {bits: 2,  name: 'Size', attr: 'x01', type: 4},
  {bits: 2,  name: 'Cmd', attr: 'xAA', type: 4},
  {bits: 2,  name: 'Req/Reply', attr: ['Req x01', 'Rep x00'], type: 4},
  {bits: 12,  name: 'Head', attr: ['xEB x90 xEB x90 xEB x90'], type: 5},
], 
  config:{bits: 26}
}
 </script> 

<script type="text/javascript">
(function() {
    try {
        WaveDrom.ProcessAll();
    } catch(e) {}
})();
</script>
@endhtmlonly

The structure of the communications register is as detailed above...

Rexon RDM150 ESTOP Retrofit

Summary

In a prior blog, minor repair work was undertaken on a Rexon drill press, model RDM 150D. The drill press came with only the standard run stop switch, no other safety or features. This blog follows the design, build and fitting of an emergency stop controller to the drill press.

Requirements

The requirements for the emergency stop controller were not strict; provide an emergency stop button on the front of the drill press. The stop action would be performed utilising a suitably rated contactor to interrupt the motor. The second feature (option) was to monitor rotation of the spindle to identify belt slippage or spindle stall whilst drilling. In the event of an error the contactor could be used to interrupt the motor.

Original Electrical Wiring

Shown below is a representation of the original electrical wiring for the RDM 150D. The main components shown in the diagram are the run stop switch and induction motor.

Rexon RDM150D Electrical

Electrical Wiring Update - Stage 1

The updated electrical wiring is shown below. The changes in the design consist of a circuit breaker, contactor, ESTOP button and controller. As the ESTOP controller and contactor operate from a supply voltage of 24VDC, a suitable AC to DC switch mode power supply is shown in the updated electrical wiring.

Rexon RDM150D Stage 1 Electrical

ESTOP Enclosure and Switch

With a clearer picture of the electrical hardware required the electrical enclosures were selected due to limited space. This was especially relevant to the emergency stop button. The switch chosen was from manufacturer EAO, model 84-5041.2B20, with double poles, normally closed contacts and internal LED. The short solder tail pins on the rear of the switch cater were ideal for shallow depth mounting enclosures.

EAO ESTOP Switch

To house the emergency stop switch, a wall mounted enclosure was utilised.

Wall Mount Enclosure

Controller Housing

Two DIN rail devices were required in the updated design, a contactor and an AC DC switch mode power supply. Staying with the DIN rail theme, a DIN rail enclosure was chosen from the Taiwanese manufacturer Dinkle. With all the hardware features required for the controller, an enclosure with 4 sets of 3 way connectors was selected. A similar to Dinkle part is DMEN-T3.

Dinkle DIN Rail Mount Enclosure

DIN Rail Electrical Enclosure

To contain items such as the circuit breaker, contactor, switch mode power supply, emergency stop controller and the sundry electrical wiring, a small plastic electrical enclosure was chosen. Supplier ABB manufacture a Europa series of enclosures which are suitable for holding DIN rail equipment. ABB Part number 1SL0880A00. This enclosure does not come with DIN rail and needed to be fitted.

ABB Enclosure

Controller Hardware Design

To perform the operation of controlling the contactor (coil), based on the position of the emergency stop button, a dedicated controller would not usually be required. Series connection of the emergency stop buttons normally closed contacts with the contactor coil would suffice. The updated design does however provide a few other options for expandability so a controller was required.

A microcontroller (Cypress PSoC) based solution was implemented in this project. This device was chosen because the internal FPGA could be used to monitor the two emergency stop inputs and activate both of the output drivers responsible for driving the contactor 24V and 0V rails, with the need for very little firmware. Certainly a code free design was not an essential feature nor intended however, using the microcontroller FPGA allowed for quicker implementation.

Hardware Features

As mentioned in the Hardware Design section, separate hardware drivers were used to drive the contactor supply rails of 24V and 0V. Displayed below is a portion of the schematic, with the two FET based switches used for driving the contactor coil.

Driver 0V

Driver 24V

The inputs to the controller were designed to convert the external 24V to the internal 5V level used. A voltage divider, with Zener protection, was used to limit the maximum voltage. Two separate inputs were used for the emergency stop contacts.

Controller Inputs

Four controller inputs were mapped to the micontrontroller, two for the emergency stop and two for the spindle stall detection option.

Controller Inputs to PSoC

The emergency stop button contained an LED which was used to feedback the the switch state. Control of the LED was achieved using a single discrete driver as shown below.

LED Driver

Mapping of the inputs and outputs to the microcontroller was performed after the IDE (PSoC Creator) project was successfully generated. Shown in the capture below is the resulting connections to the PSoC.

PSoC IO Connections

Lastly was the 5VDC power supply for the boards logic devices which included the PSoC and the output driver for the 0V.

Power Supply - 5VDC

PSoC Pin Mapping

Mapping of the PSoC pins using PSoC Creator to generate the application was made concurrently with drafting the schematic.

PSoC Pin Mapping

The capture above was taken from the PSoC Creator project which illustrates the various connections made to the microcontroller.

Below is a capture of the page responsible for monitoring of the inputs from emergency stop switch contacts, driving the contactor to switch off the drill press motor and controlling the emergency stop switch LED.

Emergency Stop Inputs and Outputs

The logic shown in the above capture was separated into three parts. Firstly the two glitch filter components provide debounce for the emergency stop switch.

Emergency Stop Switch Glitch Filter

Second were two outputs for driving the contactor FET switches for 24V and 0V.

Lastly were a pair of PWM components with slightly different timing to create the breathing effect for driving the LED.

PWM1 Configuration for Breathing LED

PWM2 Configuration for Breathing LED

Also included in the project was a tick timer, UART component for debugging, two inputs used for future options and a status LED.

Miscellaneous Project Items

With an application generated from PSoC Creator and a schematic, the controller PCB design was started.

PCB Shape

To determine the shape of the PCB a quick check of the controller enclosure datasheet was performed. The Dinkle datasheet did provide an elaborate design for the PCB shape however the more important spacing for the terminal blocks was also shown.

Dinkle Suggested PCB Layout

Using a physical Dinkle enclosure and the suggested layout from the data sheet, a PCB shape was finalised.

Control PCB Dimensions

PCB Layout

The PCB components were placed with the microcontroller, power supply and switching FET's well separated from each other. Placement of the four 3-way connectors, representing the terminal blocks on the Dinkle enclosure, were made according to the Dinkle suggested layout.

Control PCB Parts Placement

A four layer PCB was used for routing the control board. Two external signal layers and two internal planes. One of the internal planes was solely used for 0V and the second was segmented into planelets for the various power supplies.

The capture below shows the top layer route concentrating on high current paths and breaking out connections from the microcontroller.

Control PCB Top Layer Route

In the following capture the bottom layer input and output routes are shown.

Control PCB Bottom Layer Route

The capture below shows the two internal planes, 0V to the top and power to the bottom.

Control PCB 0V Plane

Note that the power plane is split into four planelets. One section was for the input supply, a second for powering ESTOP devices, a third for 5V to power logic devices and a digital 5V required only by the microcontroller.

Control PCB Power Plane

PCB Manufacture
The control PCB was manufactured by Chinese board house 3PCB (PCBWay). During the ordering process the surface finish was selected as lead free tin with an option to use gold plating (ENIG). As shown below the PCB received was gold plated.

Control PCB Unpopulated

PCB Population
As is usually performed with a new prototype PCB, sections of the design were loaded then tested in stages. For the control PCB the 5V power supply was populated then tested. This was followed by the high low switches and lastly the microcontroller. The capture shows the mostly populated PCB during testing.

Control PCB Populated

Controller Testing
For testing of the contactor driver outputs, a control register called Control_ESTOP was configured in code which enabled the contactor driver outputs. Toggling the contactor state was possible by toggling the emergency stop button. The code below shows a portion of the code to setup the micro and drive the control register.

/**
* @brief Initialise PSoC Components and ISR
*/
void Init_Components(void)
{
    Status_LED_Write(true);
    LED_PWM1_Start();
    LED_PWM2_Start();
    isr_SysTick_StartEx(isr_SysTick_Handler);
    UART_Start();
}

/**
* @brief Send firmware version to UART
*/
void UART_Print_Ver(void) 
{
    char buf[20] = {0};                 /* Init used vars */
    sprintf(buf, "%s%d%d%d", "Drill Press v" , ver_maj, ver_min, ver_build);  
    UART_UartPutString(buf);            /* Output UART buffer */
    UART_UartPutCRLF(0);
}

/**
* @brief Setup and configure micro
*/
int main(void)
{
    CyGlobalIntEnable;                  /* Enable global interrupts. */
    Init_Components();
    UART_Print_Ver();
    Control_ESTOP_Write(0x1);   /* ESTOP output follows ESTOP button */
    for(;;)
    {

    }
}

ESTOP Housing
Mounting of the ESTOP button was made utilising a wall mount enclosure which, served as the base to attach against the chassis of the drill press.

Mounted ESTOP Button

A double insulated multicore cable (3 pair) was used to connect the mounted button to the ESTOP controller.

ESTOP LED and Contactor
With the necessary switch contacts and LED connections made to the controller, the firmware was loaded into the controller using PSoC Creator. With the ESTOP button in the deactivated position, the LED was always illuminated. In the activated position, the LED pulsed between on and off. A short video of the LED cycling is shown below.

The contactor was connected to the controller and bench tested with the ESTOP switch to verify operation.

Contactor Connection

Control of the ESTOP contactor can be visualised with a Wavedrom timing diagram as displayed below. The diagram illustrates the dependency of the contactor and LED on the PSoC operating and executing code. In the diagram the initial state of the ESTOP switch is in the released position. Changing position of the ESTOP switch causes the contactor to de-energise and the LED to begin the PWM operation. Returning the switch to the original position restores the contactor and LED to energised and non-PWM states respectively.

Mounting Electrical
Mounting the electrical components in the ABB enclosure was performed using a DIN rail. This was fitted inside the enclosure and fixed with bolts to a steel flat bar (2mm) on the rear of the enclosure. Additional tapped holes were provided on the flat bar to facilitate mounting to the body of the drill press.

Mounted Electrical Hardware

The existing electrical cabling was temporarily removed to facilitate removal of the drill press motor.

Drill Press Electrical Disconnection

With the motor belt disconnected and the fixing bolts removed, the drill press motor was removed.

Drill Press Motor Removal

To access the body of the drill press frame the motor mounting plate was removed.

Drill Press Motor Mounting Plate

Two small bolts were used to attach the steel flat bar against the chassis of the drill press.

Enclosure Mounting Bar

The motor mounting plate was replaced and drill press motor mounted back onto the plate.

There were some changes to electrical wiring on the drill press, primarily because a miniature circuit breaker was added to the design. This meant that the mains power entered the new electrical enclosure first. Shown below is the wired enclosure.

Wired Drill Press Electrical Enclosure

Mounting ESTOP
To mount the ESTOP button the existing plate showing spindle speeds vs power line frequency was removed.

Drill Press Plate

Two holes were tapped into the drill press to hold the enclosure, then the button was wired and tested.

Wired ESTOP Button

Finalising
To secure the cable between the ESTOP button and the electrical enclosure a metal clip was added.

Drill Press ESTOP Cabling

Finally the cover for the electrical enclosure was fitted in place.

Electrical Enclosure Lid Fitted

Downloads

ESTOP Module Schematics

ESTOP Controller Gerber

PSoC Creator 4.2 ESTOP Controller Project

Updates

16/11/2024    Corrected link to PSoC code