Run Toit on a Pycom Wipy board

[nilwes]

Introduction

Pycom offers several ESP32-based boards ready for production, so it makes perfect sense to use one of these with Toit. I had a Wipy lying around so in this show-and-tell we’ll have a look at that one. It is a relatively simple process, even though it requires you to ensure the Wipy board is in “Boot mode” prior to flashing. In addition you’ll need an FTDI USB-to-Serial adapter and some jumper cables. Equipped with these basic tools, you’ll have your Wipy board up and running Toit code in a couple of minutes. No more MicroPython!

NOTE: This show-and-tell is for computers running Linux and macOS.

Setting up Toit on your computer

Here is a guide to getting Toit up and running on your computer. I’ll assume you have this set up already before continuing.

Also, you'll need the Toit CLI. Here are instructions on how to install what you need:

Required hardware

• A Wipy board (other Pycom boards might very well work just fine, but I have not tried it myself). Buy one here.
• A USB-to-Serial FTDI adapter (Here is one alternative and here is another one.)
• Jumper wires
• A breadboard

IMPORTANT: There are many FTDI breakouts and cables available out there. However, the most important thing is that the FTDI gear you use is made for 3.3V signal level. FTDI cables that use 5V signal level will probably fry your Wipy board.

Powering your Wipy

Even though it might be possible to power your Wipy board using power from the FTDI, you might end up with a brownout if the ESP32 as some point uses too high current. Therefore I used an external power supply to power the Wipy. You can for example pull the power from a LiPo battery, or you can do what I did: Scavenge an old USB cable, strip the 5V and GND cables, solder on a couple of jumper wires, and use these for powering the Pycom board via your computer USB port.

Hooking up your hardware

First let’s have a look at the pin-out diagram for the Wipy.

The P0 and P1 pins are used for Rx and Tx, respectively. This means that we should

1. connect the Wipy P0 pin to the Tx pin of the FTDI adapter, and
2. the Wipy P1 pin to the Rx pin of the adapter.

Connect your power source to the 5V pin and the ground to the GND pin. Finally, plug your FTDI adapter to your USB port on your computer.

Listening to your Wipy

To get a better insight in what’s going on with the Wipy, it is helpful to monitor the serial output from the device. To be able to do this, we need to figure out which port we should use. Check your ports by typing

ls -ltr /dev

This will list your ports ordered from oldest to newest, so if you connect your Wipy via your FTDI adapter to the USB of your computer, the port will show up somewhere near the end of this list. On macOS the port is probably called something like cu.usbserial-AB0JJ2KA, and on Linux it is probably called something like tty-USB0.

Now you can monitor the serial communication with the Wipy by using the Toit command

toit serial monitor

This command will ask which port you want to listen to. Pick the port you just identified from the list of ports.

If you can’t see any output, try pressing the reset button on the Wipy. This should generate some output from the board.

Ensuring you have your Wipy in Boot Mode

The Wipy must be put into Boot Mode prior to every flash. In order to do this, follow these steps:

• Cut the power to the Wipy
• Connect a jumper cable from pin P2 to GND
• Power up your Wipy.

Below is an image of the Wipy with the blue Boot Mode jumper cable connecting P2 to GND:

To verify the Wipy is in Boot Mode:

• In a terminal window, do toit serial monitor and pick the corresponding port.
• Press the reset button on the Wipy, or power-cycle it.
  The terminal should output something like

rst:0x1 (POWERON_RESET),boot:0x3 (DOWNLOAD_BOOT(UART0/UART1/SDIO_REI_REO_V2))
waiting for download

Making and running your first Toit program

Let’s start with the Hello World application, to ensure we have everything set up correctly. First we make it by running

make esp32 ESP32_ENTRY=/Users/your/path/to/toit/examples/hello.toit

NOTE: You have to enter the correct path to the folder to which you pulled Toit from Github.

Your Wipy board should be in Boot Mode, so we are ready to flash your Wipy. Do this by running the following juicy command

python /Users/your/path/to/esp-idf/components/esptool_py/esptool/esptool.py --chip esp32 --port /dev/cu.usbserial-AB0JJ2KA --baud 921600 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 40m --flash_size detect 0xd000 /Users/nils/toit/toit/build/esp32/ota_data_initial.bin 0x1000 /Users/nils/toit/toit/build/esp32/bootloader/bootloader.bin 0x10000 /Users/nils/toit/toit/build/esp32/toit.bin 0x8000 /Users/nils/toit/toit/build/esp32/partitions.bin

NOTE: You must change the path to your esp-idf folder as well as the serial port to your Wipy.

When the flashing is complete, remove the jumper cable that goes from P2 to GND and, power-cycle the device, and do

toit serial monitor

Power-cycle the Wipy board again, and it should spit out something like

rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0030,len:188
ho 0 tail 12 room 4
load:0x40078000,len:12180
load:0x40080400,len:2944
entry 0x400805c8
clearing RTC memory: RTC memory is in inconsistent state
[flash reg] address 0x3f42c000, size 0x00134000
Hello, World!
E (516) Toit: VM exited, going into deep sleep.

Note the Hello, World! message in the serial output. You're now ready to start playing with Toit on a Pycom Wipy board!

Stepping it up a bit...

The Hello, World! program is truly amazing. But its counterpart in the world of IoT is the blinking LED. Even better, the Wipy comes equipped with a multicolor RGB LED powered by the WS2812 chip. Luckily, there is a Toit package for driving this LED. Check out the package here.

The package contains an example, gpy.toit specifically made for the RGB LED on the Pycom Wipy, but the driver can of course drive any WS2812-based RGB LED strip.

Happy tinkering!

[joshk]

Thanks for the write-up!

I also came across https://www.soracom.io/blog/internet-of-microcontrollers-made-easy-with-toit-x-soracom/ which makes it look a lot easier to flash the Pycom with the Toit firmware.

Is there any downsides with using the instructions from the Soracom blog?

[joshk]

Hi @floitsch , thanks for all your help. Would it be possible to do a remote pairing session and I can show you what's going on?

[floitsch]

@joshk happy to help. the easiest is probably to just use one of the chats.
Either discord, or the chat on toit.io. We can then take it from there.

[joshk]

Thank you so much @floitsch for helping me! Everything is working now.

The two main issues were:

1. during the provision process you need to time-to-time reset the board for the process to continue to the next step successfully
2. when the process says it is reading hardware chip information, you can let it fail, then quit the rest of the steps. All that is needed is for you to manually claim the device using toit device claim

Thank you Toit team for the language and platform!

[joshk]

@floitsch I think I found out why toit serial monitor isn't working with the FiPy.

Essentially I don't think it is a FiPy issue but an issue with the Expansion Board v3

https://docs.pycom.io/datasheets/expansionboards/expansion3/

Under Differences between v2.0 and v3.0 it notes:

The FTDI chip has been replaced with a custom programmed PIC, similar to the Pysense/Pytrack/Pyscan boards. This allows our firmware update tool to automatically put the module into bootloader mode.

Additionally this points to an interesting feature of the v3 Expansion Board in that you can control bootloader mode programmatically.

[floitsch]

Interesting.
Alternatively using toit serial monitor -a should also work, as it doesn't try to reset the device.

[nilwes]

But it seems like the flashing of Jaguar went well. A few things to verify:

• Double-check that you're listening to the right port when doing jag monitor. Unplug-plugin the USB cable and see which port that disappears/reappears by running ls -ltr /dev
• Make sure your Wifi is a 2G Wifi. The ESP32 does not connect to a 5G Wifi.
• Make sure you are on the same Wifi (I have 2 different Wifis at home and sometimes my laptop switches and I cannot ping my Gpy)
• Once you know that your computer and your Fipy is on the same 2G Wifi, do a jag scan to search for jaguar devices on your local network.