Electronics

18
Feb
2022

Teensy 4.x timer interrupt example using TimerTree

void myTimerInterrupt() {
  // TODO Your code goes here
  // The following functions may be useful here:
  // Timer3.start(); // Start counting & clear counter
  // Timer3.stop(); // => stop counting but do not clear counter
  // Timer3.restart(); // => clear counter
  // Timer3.resume(); // => Start, without clearing counter
}

void setup()
{
  Timer3.initialize(20000);
  Timer3.attachInterrupt(myTimerInterrupt);
  Timer3.start();
}

 

Posted by Uli Köhler in Arduino, Electronics, Embedded, Teensy
18
Feb
2022

How to Arduino attachInterrupt() with both RISING and FALLING edge

You can use attachInterupt() with CHANGE to trigger on both RISING and FALLING flanks.

#define INTERRUPT_PIN 13 // Choose any pin with interrupt functionality here.

void myInterrupt() {
  // TODO Your code goes here.
}

void setup() {
  attachInterrupt(digitalPinToInterrupt(INTERRUPT_PIN), myInterrupt, CHANGE);
}

 

Posted by Uli Köhler in Arduino, Embedded
16
Feb
2022

Teensy 4.1 Arduino external interrupt (pin interrupt) minimal example

In setup(), use

attachInterrupt(digitalPinToInterrupt(23), myInterrupt, RISING);

to configure the interrupt on Teensy Pin 23 on the RISING edge.

Add this function, which will be called during the interrupt:

void myInterrupt() {
  // Your code goes here
}

 

Posted by Uli Köhler in Electronics, Teensy
15
Feb
2022

PyVISA Rigol DL3021 via LXI (TCP SCPI) example

First install using

sudo pip install pyvisa pyvisa-py

The following example will connec to a LXI-enabled (license required!!!) DL3021 at IP address 192.168.178.31

import pyvisa
import time

rm = pyvisa.ResourceManager()
inst = rm.open_resource("TCPIP0::192.168.178.112::INSTR")
# Query if instrument is present
# Prints e.g. "RIGOL TECHNOLOGIES,DL3021,DL3A204800938,00.01.05.00.01"
print(inst.query("*IDN?"))

# Set to constant resistance mode
inst.write(":SOURCE:FUNCTION RESISTANCE")
# Set to 3 Ohms
inst.write(":SOURCE:RESISTANCE:LEVEL:IMMEDIATE 3.0")
# Enable electronic load
inst.write(":SOURCE:INPUT:STATE On")
# Wait for value to stabilize
time.sleep(2)
# Measure!
print("Voltage: ", inst.query(":MEASURE:VOLTAGE?").strip())
print("Current: ", inst.query(":MEASURE:CURRENT?").strip())
print("Power: ", inst.query(":MEASURE:POWER?").strip())

This will print, for example:

RIGOL TECHNOLOGIES,DL3021,DL3A204800938,00.01.05.00.01

Voltage:  2.885810
Current:  0.961862
Power:  2.775752

with some power supply attached of course.

Posted by Uli Köhler in Electronics
12
Feb
2022

How to fix st-flash ERROR common.c: stlink_flash_loader_run(0x8000000) failed! == -1

Problem:

While flashing an STM32 using st-flash using a command like

st-flash write build/firmware.bin 0x8000000

you see an error message like

2022-02-12T01:31:34 ERROR flash_loader.c: flash loader run error
2022-02-12T01:31:34 ERROR common.c: stlink_flash_loader_run(0x8000000) failed! == -1

See below for a full error log

Solution

Most likely your STM32 is locked (readout protection). Use OpenOCD to unlock it, see How to unlock STM32F0x using OpenOCD for an example. Adjust to your STM32 family as needed.

Full st-flash log

st-flash 1.6.1
2022-02-12T01:31:34 INFO common.c: F0xx small: 4 KiB SRAM, 16 KiB flash in at least 1 KiB pages.
file build/mom.bin md5 checksum: da211df7131de9de15f3b6c7a96176dd, stlink checksum: 0x000d0d03
2022-02-12T01:31:34 INFO common.c: Attempting to write 11108 (0x2b64) bytes to stm32 address: 134217728 (0x8000000)
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08000000 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08000400 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08000800 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08000c00 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08001000 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08001400 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08001800 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08001c00 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08002000 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08002400 erased
2022-02-12T01:31:34 INFO common.c: Flash page at addr: 0x08002800 erased
2022-02-12T01:31:34 INFO common.c: Finished erasing 11 pages of 1024 (0x400) bytes
2022-02-12T01:31:34 INFO common.c: Starting Flash write for VL/F0/F3/F1_XL core id
2022-02-12T01:31:34 INFO flash_loader.c: Successfully loaded flash loader in sram
2022-02-12T01:31:34 ERROR flash_loader.c: flash loader run error
2022-02-12T01:31:34 ERROR common.c: stlink_flash_loader_run(0x8000000) failed! == -1
stlink_fwrite_flash() == -1

 

Posted by Uli Köhler in STM32
12
Feb
2022

How to lock STM32F0 using OpenOCD (readout protection)

openocd -f interface/stlink-v2.cfg -f target/stm32f0x.cfg -c "init" -c "halt" -c "stm32f1x lock 0" -c "reset halt" -c "exit"

This will activate flash readout protection level 1 which means you won’t be able to readout or re-write the flash. You can still perform a chip erase which will clear the readout protection – for example to flash a new firmware.

Posted by Uli Köhler in STM32
12
Feb
2022

How to unlock STM32F0x using OpenOCD

openocd -f interface/stlink-v2.cfg -f target/stm32f0x.cfg -c "init" -c "halt" -c "stm32f1x unlock 0" -c "reset halt" -c "exit"

After that, you need to physically remove power from the device in order for the reset to take effect.

Note the stm32f1x is no typo. OpenOCD uses the same backend for STM32F1x and STM32F0x.

Example output:

Open On-Chip Debugger 0.11.0-rc2
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
WARNING: interface/stlink-v2.cfg is deprecated, please switch to interface/stlink.cfg
Info : auto-selecting first available session transport "hla_swd". To override use 'transport select <transport>'.
Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
Info : clock speed 1000 kHz
Info : STLINK V2J24S4 (API v2) VID:PID 0483:3748
Info : Target voltage: 3.296172
Info : stm32f0x.cpu: hardware has 4 breakpoints, 2 watchpoints
Info : starting gdb server for stm32f0x.cpu on 3333
Info : Listening on port 3333 for gdb connections
Info : device id = 0x10006444
Info : flash size = 16kbytes
stm32x unlocked.
INFO: a reset or power cycle is required for the new settings to take effect.

Info : Unable to match requested speed 1000 kHz, using 950 kHz
Info : Unable to match requested speed 1000 kHz, using 950 kHz
target halted due to debug-request, current mode: Thread 
xPSR: 0xc1000000 pc: 0x080000c0 msp: 0x20000400

 

Posted by Uli Köhler in STM32
09
Feb
2022

Which way to mount the Raspberry Pi DSI display cable for the Raspberry Pi 7″ display

First, mount the Raspberry Pi on top of the display PCB on the back of the display.

On the bottom (display) PCB, the silver contacts of the cable should be at the top (facing the Raspberry Pi):

On the Raspberry Pi, the silver contacts should face towards the USB connectors:

Overall, it should look like this:

Posted by Uli Köhler in Raspberry Pi
09
Feb
2022

How to enable OctoPi WiFi connection on boot

First, install OctoPi to the SD card – for example, using rpi-imager: How to install OctoPi using rpi-imager

Open the boot partition on the OctoPi SD card and create a file wpa_supplicant.conf there, with the following content:

country=de
update_config=1
ctrl_interface=/var/run/wpa_supplicant

network={   
   scan_ssid=1
   ssid="MyWifi"  
   psk="abc123abc"
}

Always set the correct country code at the top ! If you don’t set it correctly, it won’t work!

Set ssid to the name of the wireless network.

Set psk to the wifi password.

Posted by Uli Köhler in 3D printing, Raspberry Pi
09
Feb
2022

How to install OctoPi using rpi-imager

First open rpi-imager:

then select Choose OS

Sroll down to Other specific-purpose OS (do not click on Other general-purpose OS, even though it sounds similar!)

Click on Other specific-purpose OS:

Now click on 3D printing:

Click on OctoPi:

Now click on OctoPi (stable):

Now click on Choose Storage to select the SD card you want to write the image to:

Click on the correct device to select it – double check to make sure you have selected the correct device !

Now click Write to download the image and write it to the SD card:

and now grab a coffee since it will take a couple of minutes to write:

Posted by Uli Köhler in 3D printing, Raspberry Pi
09
Feb
2022

How to enable Raspberry Pi (Raspbian) WiFi connection on boot

Open the boot partition on the Rasbian SD card and create a file wpa_supplicant.conf there, with the following content:

country=de
update_config=1
ctrl_interface=/var/run/wpa_supplicant

network={   
   scan_ssid=1
   ssid="MyWifi"  
   psk="abc123abc"
}

Always set the country code at the top ! If you don’t set it correctly, it won’t work!

Set ssid to the name of the wireless network.

Set psk to the wifi password.

Posted by Uli Köhler in Raspberry Pi
09
Feb
2022

How to fix apt E: Unable to locate package rpi-imager

Problem:

While trying to install rpi-imager using

sudo apt install rpi-imager

you see this error message:

Reading package lists... Done
Building dependency tree       
Reading state information... Done

No apt package "rpi-imager", but there is a snap with that name.
Try "snap install rpi-imager"

E: Unable to locate package rpi-imager

Solution:

sudo apt -y install rpi-imager only works on Raspbian. On Ubuntu etc, you can install rpi-imager using

sudo snap install rpi-imager

Then start it using

rpi-imager

Posted by Uli Köhler in Linux, Raspberry Pi