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4. Embedded Programming

Hero Shot of the Week

circuit

Summary

So this week I learned about Keep calm and debug. I think I did more debugging than actual learning.

Work Process

I did some coding back in school and also in university. In school I had build a car (with arduino leonardo (?)) that can be controlled with a phone. That was +-10 years ago. In university we used python and R for data Analysis & Statistics.

Intro

Henk and Leo made an introduction for embedded programming.

How to choose an microC:

  • physical pins
    • how many I/O ports do I need
    • do I have analog I/O
  • power consumption
  • microC
  • I/O devices
  • speed
  • environment
  • cost

Analog Signal :

  • Voltage change
  • measured with oscilloscope

Digital Signal :

  • 0s and 1s (binary)
  • measured with logic analyzer

And an interesting video.

Setups

XIAO RP2040 & Arduino IDE

Code to use in the Arduino IDE settings to add the XIAO RP2040:

https://descartes.net/package_drazzy.com_index.json,
https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json,
https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json,
https://raw.githubusercontent.com/qbolsee/ArduinoCore-fab-sam/master/json/package_Fab_SAM_index.json

Here is a setup guide

TLDR, go to : File > Preferences, and fill Additional Boards Manager URLs with the above URLs.

We played around with LEDs.

First the red LED on the board.

Than the RGB led with the FastLED library and the CRGB function.

VSCode

Addon for VS Code:

  • PlatformIO
  • Raspberry Pi Pico
  • Wokwi Simulator

For setup you can follow Leo's guide. It also explains how Platform IO works. And solutions for debugging windows issues.

For Windows 10 Home

So I needed to do some magic as I am on windows 10 home.

This is the following magic in CMD with admin privileges:

git config --system core.longpaths true

FOR %F IN ("%SystemRoot%\servicing\Packages\Microsoft-Windows-GroupPolicy-ClientTools-Package~*.mum") DO (DISM /Online /NoRestart /Add-Package:"%F")

FOR %F IN ("%SystemRoot%\servicing\Packages\Microsoft-Windows-GroupPolicy-ClientExtensions-Package~*.mum") DO (DISM /Online /NoRestart /Add-Package:"%F")

Than some more magic on other parts with Run and Group Policy edits. But you can follow Source 1 for that.

MicroPython

Need an OS on the microcontroller to work. This makes it that it only works with more powerful controllers.

Wiki

It is indentation sensitive.

Micropython seems to be a little more complicated to work with.

Simulators

Wokwi

I tried to simulate one of the temperature sensor present in Wokwi. I used the template given in their documentation, but there is an issue with the conversion from Analog to °C. The value inside the log is negative for most of the time. I get a 0°C print when the sensor is set to 61°C...

Sim

Lets start with my final project

I asked in mattermost what is the better way to work.

Creating a new repo where I put my code
Or
Creating it inside my webpage repo.

Got no answer so I went with the second one while keeping it on a new branch.

ESP32-S3

So I think I will use XIAO ESP32 S3 because:

  1. I have it at hand (3 of them)
  2. it works with MESH networking (that I will need for my final project)
  3. Harder to hack. (But the data sent is not sensitive data...)

Cons:

  1. It uses a lot of power

To start I wanted to experiment on wokwi. Found a temperature sensor but it is analog output, so I need a ADC. But which pins accept that ? Lets go read some Data Sheets CTRL+F reveals that the ESP has an internal temperature sensor. I wonder if I can also access it

In the end I have found the pinout on Seeed's webpage.

PinOUT
So I can just use A0 to A5 & A8 to A10 for direct analog connection.

While searching on why I can't have the right Temp, I have found the following. The conversion depends on the ADC bit definition. It also depends on the T sensor. And also if we have a resistor in the path. So while digging in the Data Sheet to found the bit definition of the ADC (that I still did not found) I stumbled across the following link for the Technical Reference Manual. This is too much of a read...

But it seems that the (SAR) ADC is a 12 bit definition. CTRL+F worked after all.

Weekend passed.

Back to my FabLab, I had a chat with Henk. We tried to trouble shoot the simulation but at one point we dropped it to directly work with the temperature sensor VMA320 that I have. So I connected all the different components on the bread board. I also found a doc which talked about noisy ESP32 values. So I added a 0.1uF Capa to the circuit.

Compiler Debugging

Then, when I tried to build the code I run into another issue. VSCode / PlatformIO was complaining about not having a compiler. So I check the link given in the error message. Than I did not follow it and instead activated my VPN to circumvent the university firewall. And it worked 🤣 .

After several attempts of builds and error corrections (the number of ; missing...) I tried to upload it to the ESP32-S3.

I had an issue where it said no port specified. So I connected my ESP to my laptop...

Than I had another type of error message:
(they don't want to stop coming)

A serial exception error occurred: Cannot configure port, something went wrong. Original message: OSError(22, 'The I/O operation has been aborted because of either a thread exit or an application request.', None, 995)
Note: This error originates from pySerial. It is likely not a problem with esptool, but with the hardware connection or drivers.
For troubleshooting steps visit: https://docs.espressif.com/projects/esptool/en/latest/troubleshooting.html
*** [upload] Error 1

The f*ck ?!

To trouble shoot I first checked in Arduino IDE to see if I have the same issue. For this I added the following board manager.

Still have an error. But a different one ??? No. It seems that they just phrase it differently.

😓 😫

A serial exception error occurred: Cannot configure port, something went wrong. Original message: PermissionError(13, 'A device attached to the system is not functioning.', None, 31)
Note: This error originates from pySerial. It is likely not a problem with esptool, but with the hardware connection or drivers.
For troubleshooting steps visit: https://docs.espressif.com/projects/esptool/en/latest/troubleshooting.html
Failed uploading: uploading error: exit status 1

So I went back to the basics. Blink the LED. Now arduino IDE uploads the code but still gives the error message ?! WTF ?!

Click to Expand Sketch uses 296672 bytes (8%) of program storage space. Maximum is 3342336 bytes. Global variables use 19848 bytes (6%) of dynamic memory, leaving 307832 bytes for local variables. Maximum is 327680 bytes. esptool.py v4.8.1 Serial port COM21 Connecting... Chip is ESP32-S3 (QFN56) (revision v0.2) Features: WiFi, BLE, Embedded PSRAM 8MB (AP_3v3) Crystal is 40MHz MAC: e8:06:90:a0:fa:88 Uploading stub... Running stub... Stub running... Changing baud rate to 921600 Changed. Configuring flash size... Flash will be erased from 0x00000000 to 0x00004fff... Flash will be erased from 0x00008000 to 0x00008fff... Flash will be erased from 0x0000e000 to 0x0000ffff... Flash will be erased from 0x00010000 to 0x00058fff... Compressed 20160 bytes to 12988... Writing at 0x00000000... (100 %) Wrote 20160 bytes (12988 compressed) at 0x00000000 in 0.3 seconds (effective 480.2 kbit/s)... Hash of data verified. Compressed 3072 bytes to 146... Writing at 0x00008000... (100 %) Wrote 3072 bytes (146 compressed) at 0x00008000 in 0.1 seconds (effective 235.7 kbit/s)... Hash of data verified. Compressed 8192 bytes to 47... Writing at 0x0000e000... (100 %) Wrote 8192 bytes (47 compressed) at 0x0000e000 in 0.1 seconds (effective 481.0 kbit/s)... Hash of data verified. Compressed 296784 bytes to 157581... Writing at 0x00010000... (10 %) Writing at 0x0001bc07... (20 %) Writing at 0x00027d18... (30 %) Writing at 0x0002d471... (40 %) Writing at 0x000333a5... (50 %) Writing at 0x00038ce1... (60 %) Writing at 0x0003e58a... (70 %) Writing at 0x00043ec2... (80 %) Writing at 0x0004b5d8... (90 %) Writing at 0x00054ac8... (100 %) Wrote 296784 bytes (157581 compressed) at 0x00010000 in 2.1 seconds (effective 1123.2 kbit/s)... Hash of data verified. Leaving... Hard resetting with RTC WDT... A serial exception error occurred: Cannot configure port, something went wrong. Original message: PermissionError(13, 'A device attached to the system is not functioning.', None, 31) Note: This error originates from pySerial. It is likely not a problem with esptool, but with the hardware connection or drivers. For troubleshooting steps visit: https://docs.espressif.com/projects/esptool/en/latest/troubleshooting.html Failed uploading: uploading error: exit status 1


Following this documentation, I somehow managed to make it alive (with the blink code).

TLDR: You need to activate the bootloader mode.

Than copy pasting my code (with some edits to have more Serial.print, than adding ; as I forgot them) I managed to make my code work.
I still have negative temperature when it should be around 20°C. But that is a different issue.

Now I still need to figure it out why it does not work in VSCode

Seems like putting the ESP32 into the bootloader mode again (previous link), than uploading corrected the issue. The first time I also needed to use the reset button of the ESP.
This took me longer than I have wanted.

I also tried a third method to calculate the temperature, but still have the wrong T.

Temperature Sensor journey

FINALLY!!!

I have a TempSensor code that works and give the right (range) of temperature.

T values

This was a long journey.

Circuit

Lets start at the beginning.

First I wired the board as described in the VMA320 Manual. So with 5V.

The first code I tried using, was the code given in wokwi. That did not work. Even after changing the bit ADC definition as proposed in this overflow help to the correct 12bit.

The 2nd code was from Stackoverflow. But still couldn't get the right T.

3rd was given to me by Henk. It was a micropython version from SunFounder. Even converting it to C it wasn't working.

Than I walked home. On the way it hit my. Why did I not search for it on FabAc ?

4th I found the page of David Erkan. (Week 16). But somehow even his code did not work. (Found this out the next day when I went back to work, did not bring the setup to home).

5th was the FabGPT version. First it gave me a bullshit answer for a different thermosensor (it wasn't even a thermoresistor...). So when I pointed it out it corrected itself. Back to the FabLab the code was still not working.

(Full FabGPT conversation so far.)

6th was from CircuitBasics. I got quite a better answer when I put a - in front of a R (for resistor) parameter. But that physically would mean nothing... A friend who was here for some other work was horrified of my troubleshooting the issue with a negative sign.

7th attempt was from AdaFruit. Still not working. BUT. Changing the 1023 to 4095 (ADC bit definition) AND changing the Sensor to 3.3V source made it work. (At least I am in the correct T range. Unfortunately I have no control sensor to verify it.) But using 3.3V makes no sense as the manual clearly says 5V...

Looking back at all those version, they all use the Steinhart equation. But in different variations and with different constants. (You can check the different code on my git history.)

So was the issue all along that I was using the 5V ? Who knows. But the manual said 5V... This shit took me +- 2 days... Frustrating.

Anyway. Now it works.

Here is the circuit:

circuit

I will move to the next step which is ... No idea...

Reading Articles

Different articles were shared in matermost. I will try to make my resume on them here. (Because I am still not sure if what I did is what was needed to be done 😅)

Choosing a microcontroller

A Guide To Making The Right Microcontroller Choice Choosing a microcontroller

The idea here is that controllers can be put into 3 categories:

1) simple process control

* Simple algorithm
* smaller operations (32bit processor)
* slower I/O process (max 10 MHz)

2) computationally intensive tasks

* High Volume Data (ex: playing Doom)

3) IoT products

* High wireless connectivity
* 3D graphics
* fast ram

Than knowing what our project is supposed to do we can narrow down our controller selection.

Of course you can also factor it the fact that you want to discover knew ways to code. That would lead to different microcontrollers that you are used to use.

Digital Signal Processing Applications

How to Choose a Microcontroller for Digital Signal Processing Applications

How much bit do you need

  • higher bit allows mathematical procedure with larger numbers
  • BUT it is also important to look at other components / parts bit number (register, address bus, etc)

Clock speed

  • instructions / sec (clock frequency) ≠ clock cycles / sec
  • in general, if you are in the same family of controllers, choose the controller with the higher clock frequency

Fixed-Point vs. Floating Point

  • floating-points seems to better work with mathematically intensive applications
  • if you need that power, go for a controller with a floating-point coprocessor

Learning Outcome

What have I learned. Well. Mostly is keep calm and throw shit at your code. Or at your debugging. At one point it will work out.

Anyway. Frustration apart. I discovered new IDEs. Rediscovered coding languages. I did some C/arduino back in school but that was like 8 years ago. Same for python but only 6 years ago. So rediscovering the pain of forgetting a ; was... mmh... fun but frustrating ?

Than debugging is a pain in the ass. I used up so much of my FabAc time... But the pleasure of founding a solution is really nice. (It doesn't mean that I understood why it wasn't working in the first place.)

Assignment Check

  • group assignment:
    • demonstrate and compare the toolchains and development workflows for available embedded architectures
  • individual assignment:
    • browse through the data sheet for your microcontroller
      • done
    • write a program for a microcontroller,
      • and simulate its operation,
        • Somewhat done
      • to interact (with local input &/or output devices)
        • does interaction with the simulated T sensor count ?
      • and communicate (with remote wired or wireless connections)
    • extra credit: test it on a development board
    • extra credit: try different languages &/or development environments