PSoC to Tracer MPPT 1210RN 2210RN 3215RN 4210RN with Bluetooth and Datalogger

Summary
Although the early EPSolar MPPT Tracer series with remote display have been surpassed by improved MPPT models with inbuilt LCDs, there are plenty of the earlier models that remain in operation. This project is Cypress PSoC 4 BLE based and features connection to the Tracer MPPT, load control, Bluetooth and data logging of the MPPT data.

MPPT
A number of other people have used the EPSolar MT-5 display to reverse engineer the communications protocol, however there was PC software from the same manufacturer which performed all the same functions, possibly more.

EPSolar Tracer RN MPPT

At last glance of the EPSolar website the Tracer series had reached obsolescence and the PC software on the site no longer supports the Tracer series.

Hardware
Initial documentation for the MPPT connections were taken from a site by Steve Pomeroy, another two sites by John Geek. The 8 way RJ connections to the Tracer were drafted with an optional zero ohm link added such that the MPPT could power the project. Buffers were added to the transmit and receive lines, although not a necessity, to ensure some protection for the PSoC from the real world.

EPSolar Tracer RJ45 Connections

For the display an OLED or LCD capable of being powered from 3.3V for both the logic and backlight was selected. In most instances this results in the LCD contrast voltage being negative however this was generated by the PSoC using the circuit shown below.

LCD Connections

Four momentary push buttons were used instead of the Cypress Capsense feature. This solution using switches was chosen only due to the design of the hardware as the PCB was to be mounted inside a box and away from the lid.

Buttons / User Interface Connections

The power supply regulator was chosen to be small and the usual buck topology. The LMR14203 has been my default single output regulator for some time, certainly there are newer devices with higher efficiency in the low current region of operation. In the event the display that was chosen could not have the backlight operate from 3.3V, a linear 5V regulator was added for testing.

Power Supply Connections

Even though the design incorporated Bluetooth, USB was added for debugging, downloading of data and upgrading of the PSoC. Field upgrades would be possibly by using the PSoC bootloader, a program allowing the active application to be updated some time in the future. The FTDI FT230X was chosen for the USB implementation however for those looking for a similar priced and reliable solution the Cypress CY7C65213A-32 would also be a good choice.

FTDI USB Connections

The PSoC selected was the CY8C4247LQI-BL483, which features a 48MHz System Clock, 128K FLASH and the all important Bluetooth. Although the PSoC4 libraries did not support SD at the time of writing, there are a few alternatives from the PSoC Community.

PSoC Connections and Supply Filtering

Lastly bringing all the sub-sheets together is the top sheet as shown below.

Project Top Sheet

PCB Enclosure
The PCB was designed to fit into a plastic enclosure with a clear lid, no bells no whistles. A Ritec case from a local supplier was used, the Altronics H0324.

Altronics H0324 enclosure

With the enclosure size selected the PCB dimensions were set to 98mm (W) x 75mm (H).

PCB Design

For the schematic and board design Altium was chosen since the board was mixed logic with RF. This combination was always in my mind a four layer board. The board layer stack would follow the usual two middle power planes and signals on the outside layers.

There were a number of parts added to the component database although none more interesting that the meandered inverted-F antenna (MIFA) to suit the PSoC4 BLE part. The antenna design was well documented in the Cypress Application Note - AN91455. This antenna was implemented as described on Page 10 of the Application Note.

PSoC4 BLE MIFA 

The board shape was drawn and a work guide added for the position of the four push buttons, then all components were place on the PCB.

Tracer MPPT Interface Board

With some quick shuffling of parts then an idea of the layout could take place.

Tracer MPPT Interface Board Parts Placement

Parts positions were changed on the PCB with some connectors and the SD card moved to the bottom layer.

Tracer MPPT Interface Board Final Part Placement

A few hours later the final route is shown below.

Tracer MPPT Interface Board Final Route

The board in 3D shows the stacking of the LCD and logic board.

Tracer MPPT Interface Board with LCD

PCB Prototype

The PCB was hand populated for both top and bottom layer. Some last minute modifications were made to the LCD connector and backlight control because the four line LCD had to be changed to another manufacturer. LCD supply pins were swapped.

Top Layer MPPT PCB Populated

Bottom Layer MPPT PCB Populated

To mount the LCD to the MPPT board, a male pin header was soldered to the bottom side of the LCD. To space the LCD and MPPT board 12mm tapped metal spacers were used.

Spacers for MPPT PCB and LCD

USB Check
Two of the hardware connections that were used for debugging this particular project were the Cypress MiniProg3 programmer and the USB port. Certainly the LCD or on-board status LED could also be useful although the background debugger and serial port usually work sufficiently.

With the USB connected between the MPPT board and a Windows PC, the FDTI chip was configured using the FTDI application FT Prog. This application was used to disable three unused CBUS pins and reconfigure the fourth for USB bus voltage detection.

FT Prog Scan

The Scan command was issued the the FTDI device was located.

FT Prog Default CBUS Settings

From the list shown in the Device Tree pictured above, the 'Hardware Specific' item was expanded and the 'CBUS signals' entry was selected.

FT Prog Updated CBUS Settings

The settings were modified as shown above which enabled voltage sensing for the USB - VBUS_Sense. All other CBUS pins were unused and therefore tristated.

FT Prog Program

To save the CBUS settings changes using FT Prog, the 'Program' command was used. As shown in the capture above a 'Program Devices' dialog allows for confirmation of the Program process then subsequent programming.

RealTerm Loopback Test for MPPT Board

In order to test the USB a dummy PSoC application was made to loopback the Tx and Rx pins, P0.4 and P0.5 respectively. RealTerm was then used to test the loopback at 921600 - no issues were noted.

Software - Prototype
After the initial hardware checks of the boards power rails some initialisation code was written to check the LCD, buttons and communications. Below is an example of the initialised LCD.

Initialised LCD for Testing

A prototype project, certainly with some bugs, is available for download below.

Prototype Tracer PSoC MPPT Interface

The prototype project implements communications to the Tracer MPPT and display of current MPPT readings to LCD. Some of the current MPPT readings are also sent to the USB port for logging.

Serial Data Logging
The data logging 'USB output' was rather raw code with the sole purpose of providing a console output capable of being imported into Microsoft Excel. The UART Update function was called every minute and send some basic information to a terminal application.

void UART_Update() 
{
    char UART_Buf[20];
    uint16_t UART_temp;

    UART_UartPutString(LINE1_PV);
    UART_temp = MPPTPanelVoltage;                           /* Temp memory to modify for display */
    sprintf(UART_Buf, "%d.%02d%s%c", (UART_temp/100), (UART_temp%100),"V",0x9);
    UART_UartPutString(UART_Buf);
    UART_UartPutString(LINE1_BV);
    UART_temp = MPPTBatVoltage;                             /* Temp memory to modify for display */
    sprintf(UART_Buf, "%d.%02d%2s%c", (UART_temp/100), (UART_temp%100),"V ",0x9);
    UART_UartPutString(UART_Buf);   
    UART_UartPutString(LINE2_BI);  
    UART_temp = MPPTBatteryCurrent;                         /* Temp memory to modify for display */
    sprintf(UART_Buf, "%d.%02d%s%c", (UART_temp/100), (UART_temp%100),"A",0x9);
    UART_UartPutString(UART_Buf);
    if (System.MPPT_Load_Is_On == true)
    {
        UART_UartPutString(" Load On\r\n");
    }
    else if (System.MPPT_Load_Is_On == false)
    {
        UART_UartPutString(" Load Off\r\n");
    }

}

Shown below is an example of the data output to a terminal application.

MPPT Example UART Output

The output panel voltage displayed in the terminal window was also used to verify the position and angle of the solar panel. Moving the solar panel a few degrees off axis to the sun appeared to make no appreciable difference in the readings.

MPPT Protocol
The protocol was verified and confirmed in another of my blogs which can be found at http://electronicmethods.blogspot.com.au/2017/03/tracer-mt-5-to-mppt-communications.html

SD Card
The SD card implementation was scheduled to use the Element 14 community project #50 implementation for the PSoC4, which uses a modified version of the Segger / Cypress EmFile. In early part of '18 an article appeared Hackser.io with an implementation using Segger libraries by Hima from Cypress allowing SCB (Serial Communication Block) or UDB's (Universal Digital Blocks) for communications to the SD card.

Downloading and compiling the example from Hackster illustrated how easily the project could be changed between SCB or UDB's. Another feature buried in the API's are related SD card functions which are non-blocking. For full details see the Hackster.io site with credit to Hima. Note the Segger library license requirement.

In the capture below, are the two additional directories for adding the SD Card libraries to the MPPT project.

PSoC4 SD Card Libraries Compiler Entries

Similarly the Linker references one additional directory.

PSoC4 SD Card Library Linker Entry

To test the SD Card the appropriate File System header file was included and blocking writes were made to the SD card - a snippet is shown below.

#include <FS.h>
...
...
if ((pFile) && (SD_Removed_Read() == false))
    {      
        UARTCrLf[0] = 0x0a;UARTCrLf[0] = 0x0d;

        FS_Write(pFile, PV_string, strlen(PV_string));
        FS_Write(pFile, "," , 1u);
        FS_Write(pFile, BV_string, strlen(BV_string)); 
        FS_Write(pFile, "," , 1u);
        FS_Write(pFile, BI_string, strlen(BI_string)); 
        FS_Write(pFile, "," , 1u);
        FS_Write(pFile, TE_string, strlen(TE_string));
        FS_Write(pFile, "," , 1u);
        FS_Write(pFile, LOAD_string, strlen(LOAD_string));
        FS_Write(pFile, UARTCrLf , strlen(UARTCrLf));

    }

The rather inelegant code above was for testing opening of the log file written to the SD card, by Excel, Libre Office or another similar application with CSV capabilities. Shown below is a sample of the log from the SD card.

0.00V,13.34V,0.00A,25C,OFF
0.14V,13.34V,0.03A,25C,ON 
0.14V,13.32V,0.02A,25C,ON 
0.14V,13.32V,0.02A,26C,ON 

Next up scheduling control of the SD card....

Beta Layout Reflow Controller with USB (FTDI FT311) connection to Android Phone

Summary
As a follow-on from the original Beta Layout post, this information shows one method of connecting the Beta Layout reflow controller serial interface, to an Android compatible phone with some off the shelf hardware.

Reflow Controller
The Beta Layout Reflow Controller (V2) provides a connection to it's inner workings through a serial port (RS232), 9 pin D type connector. While moving a laptop to the reflow controller every time the controller requires and adjustment, there are devices such as the FTDI USB specific hardware to suit interfaces with Android phones.

USB Development Module
One of these devices, FT311, is a plug and play USB Host chip for Android devices. There is an associated development module, UMFT311EV, that provides a number of interfaces, one being RS232. The header pinouts on the module suits off the shelf adaptor boards and some shields.

FTDI FT311 Dev Module

RS232 Adaptor
The FTDI board is TTL so an RS232 shield such as the model from DFRobot can be used to make the required conversion.

DFRobot RS232 Shield

While the 5V and 0V power header is pin compatible between the boards, the communications header with TX, RX, CTS and RTS requires a few jumpers.

Linking Interboard TTL
From Section 4.1.2 of the UMFT311EV datasheet the hardware connections are identified.

UART Hardware Pinouts

Since the hardware handshaking is not used these two pins 5 and 6, can be joined together for now.

DF Robot J1 Pinouts

The corresponding Tx and Rx connections as shown on the DF Robot shield schematic, follow the Arduino shield mapping and are available on pins 1 and 2.
To make the modifications, pins 1 and 2 on the Robot shield are snipped off or pulled to the side as not to mate with the FT311 development module.

DF Robot Jumper Connections

Using wire links or a pin header inserted into J1 on the Robot shield, pin 1 RXD is linked to pin 4 or RXD for the USB. Then pin 2 TXD is linked to pin 3 or TXD for the USB. Lastly pins 5 and 6, CTS and RTS are linked.

The FT311 module and Robot shield can be fitted together.

RS232 Cable
Since both the communications devices sport a 9 pin female D connector a null modem cable is required between them.

Hardware Assembly
The other two pieces of hardware required are a power supply or plug pack to suit the development module and the USB charging cable used with the Android phone.

Assembled FT311 and RS232 Shield Hardware

Android Terminal Program
To communicate with the Development board FTDI provide AOA HyperTerm, which is a basic terminal interface for the Android. Available on the Google Play Store and passes the Android MyPermissions and 360 Security checks.

With the HyperTerm application installed and the hardware setup powered then phone can be connected to the charging cable. In doing so the HyperTerm application is automatically launched.

AOA HyperTerm Application from FDTI

To configure the communications select the Settings button then choose the interface required. For the Beta Layout reflow controller, 9600, 8, N, 1 are the communications settings and since the hardware handshaking is looped at the DF Robot shield, the default settings in HyperTerm can be used.

AOA HyperTerm Communications Settings

After selecting Configure commands can be exchanged with the reflow controller.

AOA HyperTerm Communications Settings Confirmation

Starting with sending help and a CR the list of available commands is returned.

Beta Layout commands on AOA HyperTerm

In the screenshot above the help screen and status data is displayed in the HyperTerm window. The status information is configured for bursts at five second intervals which is used to track the starting and operational temperatures.

The final setup of the hardware as used on the bench is shown below. For similar and compatible Android USB hosts, shields or development kits the same process should be possible!

Beta Layout, USB Dev Kit, RS232 Shield with Android and AOA HyperTerm

Beta Layout Reflow Controller with Sunbeam BT2600 Mini Bake and Grill for Reflow Soldering

Summary
While designing a prototype circuit for an LED torch it became apparent that many of the white LED controllers were surface mount leadless devices. Many of these devices have exposed pads meaning that standard soldering with an iron can be difficult.

It is possible to solder smaller devices with exposed pads by directly applying the heat beneath the device through thermal vias in the PCB, or use the oven in the household kitchen to reflow, however neither of these are ideal solutions.

Reflow Controller
Beta Layout have for some time sold a Reflow Controller. This controller (Version2) has been reviewed with the Severin oven which Beta Layout provides however there are no reviews for ovens available locally in Australia. 

Beta Layout V2 Reflow Controller

At the time of writing the Beta Layout controller sold for €119 plus shipping. There are a number of kits and Arduino style solutions on the web although for an off the shelf solution this was worth trying the controller with a locally available oven to determine suitability for home reflow soldering.

Reflow Oven
The only factor determining the oven to choose was the maximum load of the reflow controller which, for the version two model, is 1500W.

Searching the local market results in a grill from Sunbeam BT2600 with elements top and bottom. The oven retails from the GoodGuys for just under $60 AUD.

Sunbeam BT2600 Oven

Noteworthy Items
It should be noted that as the controller is European made the associated mains plug and socket suit the European market. No option to order an Australian plug to female IEC plug or male IEC to Australian socket.

Oven and Reflow Controller Learn Cycle
Beta Layout's controller is for the most part plug and go. On the hardware side there is the main AC power, oven AC power and the thermocouple. 

A learning cycle must be completed before the controller can be used. The thermocouple can readily be lashed to a dummy PCB (spare leaded components or enamelled copper wire) and placed in the most central position inside the oven.

Sunbeam BT2600 Oven Inside

With the door down the upper and lower heating elements are easily visible. On the front control panel the oven is switched to 240C and the timer set to OFF.

The dummy PCB is placed in the middle of the oven, door closed, power ON and the learning process is ready to start.

Test PCB for Learning Cycle

Once the learning button is pressed the oven comes to the required temperature and then the oven switches off. Subsequently it should be noted that the oven was left running standalone, in the garage, for an additional 10 min to reduce some of the VOCs. Time for a test board.

Test Board and Oven Temperature Profile

For the reflow tests the same PCB is used. A few resistor pad pairs are cleaned with flux, solder paste added and surface mount resistors applied. To apply the solder paste without a stencil, a syringe with a 0.5mm needle allows a relatively clean and controlled application of the paste.

With the PCB placed in the middle of the oven, the door is closed and the solder button is pressed on the controller. The thermocouple was left attached to the test PCB.

Beta Layout Controller - Preheat Stage

Several minutes later the reflow process has completed and the oven has cooled down sufficiently that the PCB can be checked.

Test PCB after Reflow

Inspecting the PCB, all joints to the resistors are clean and the component alignment is good - not faultless. Changes to the profile may help eliminate some bubbling on the joints.

Before operating the oven again the RS232 port on the controller is connected to a laptop and a standard terminal program, TeraTerm. Using the controllers interface the automatic temperature measurements were configured to be output at 5 second intervals. A number of cycles were run across the day as the ambient temperature increased.

Below are the graphed profiles of the oven with some minor variation in the starting ambient temperature.

Reflow Oven Temperature Profile

Several subsequent tests using the oven yielded repeatable reflow results with similar sized PCB's. Reducing the oven thermostat from 240C to 210C made little difference to the results however reducing the thermostat to 190C caused issues with proper wetting and should be avoided.

Shortly after the reflow cycle was complete the door of the oven was opened and a thermal image taken. Some of the heat has already escaped from the opening of the door.

BT2600 thermal image shortly after reflow

The temperature profile used by the controller can be manually configured through the serial interface using a terminal program. 

In summary this combination of controller and oven is a valuable addition to the prototyping hardware setup which can yield excellent results for the home hobbyist.

Wireless remote controlled rocket launcher with Atmel ATMega328 for Arduino - Version 2

Summary
This is the second version of the Rocket Launcher project. This includes improvements for safety, a microcontroller upgrade and additional features. With the maker community now so large this design will be based on the Arduino with custom hardware.

Improvement Summary

To improve the launcher design some items were considered.

1. Reverse Battery Protection
   Prevent false launches when a engine is fitted and the battery is wired in reverse
2. Igniter Connected
   Load (igniter) sense addition to show if the igniter is still connected
3. Low Battery A defined threshold and indicator showing the low battery condition
4. Alternative Transmitter and ReceiverAllow an alternative to the communications hardware
5. Improve User InterfaceAllow for interfacing to an LCD to provide more information and control
6. Upgraded MicroLarger microcontroller for the additional features listed above

Change Summary
Starting with the new Atmel microcontroller each of the improvements will be reviewed.

1. MicrocontrollerThe Atmel ATMega328P is featured prominently in Arduino designs and is a well established micro. This device lacks some of the features newer devices offer such USB interfacing on the 32U4, however it is also half the price
   

   

   ATMega328P (TQFP Footprint)

2. Reverse Battery ProtectionA high current diode with a low forward voltage (Schottky) added to the circuit to prevent reverse battery issues
3. Igniter Active
   Detection of the battery voltage on the the MOSFET drain to indicate that an igniter is connected, analog to digital (AD) conversion
4. User InterfaceLCD header integrated into the next circuit board with buttons for control and feedback
5. Alternative Transmitter and Receiver
   Multiple footprints for receiver hardware on the circuit board
6. Low Battery
   The Sealed Lead Acid (SLA) battery will be monitored with a Zener diode dropper with a resistor divider
7. Data Logging
   With all the new metrics being gathered it makes sense to add an SD card

Design Notes
Aside from the new micro some additional buffering will be added to protect against ESD and other forms of damage.

Part Selection
Up next the alternative transmitter and receiver, then handling the level translation for the SD card...