OpenIPC
/
wiki
mirror of https://github.com/OpenIPC/wiki.git
1
0
Fork 0
Code Activity
wiki/en/hardware-programmer-ch341a-...

2.8 KiB
Raw Blame History

OpenIPC Wiki

Table of Content

CH341A Programmer

Fixing high voltage bug

Early versions, prior ver. 1.7, of the cheap and popular CH341A Mini Programmer have a nasty bug where voltage levels on data lines remain at 5V despite the programmer being set to 3.3V with the jumper.

@ddemos1963 came out with an interesting hack to fix the issue in an efficient and artsy way.

Here's what you do.

Sever the connection between between 5V power line and the CH341A chip. With a sharp utility knife, cut the trace on the back of the programmer board.

Connect 3.3v output leg of the voltage regulator to pin 9 of CH341A IC bridging it to a corresponding trace at a nearby capacitor.

Restore power to the chip re-routing 3.3V voltage from 3v3 pin to pin 28 of CH341A IC through 5V pin connector on the header.

Troubleshooting

libusb: error [get_usbfs_fd] libusb couldn't open USB device /dev/bus/usb/001/003, errno=13
libusb: error [get_usbfs_fd] libusb requires write access to USB device nodes

If you get an error message like this running a programming software, you need to adjust permissions on the USB port for that device.

Create a udev rule file

sudo vi /etc/udev/rules.d/99-ch341a-prog.rules

add the following content in the file:

# udev rule that sets permissions for CH341A programmer in Linux.
# Put this file in /etc/udev/rules.d and reload udev rules or reboot to install
SUBSYSTEM=="usb", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="5512", MODE="0666"

save the file, reload udev

sudo udevadm control --reload-rules
sudo udevadm trigger

then unplug the programmer and plug it back in a USB port.

Power supply isolation

We also recommend insulating the output going to the VCC terminal block and clamps with a piece of heat pipe to prevent power supply to the board through this circuit. Power supply can trigger the processor to start up and the work of reading/writing information from the flash chip will be disrupted.

Software