Posted on September 18, 2015 at 08:22Hi Sebastian,
I know, the Thread is very old, but I HAD the same problem. The solution tooks me like two Weeks to find! It's the Bit-Timing register on the PEAK PCAN Dongle, or better said: the sampling point.
If you choose the standard settings from the peak api the sampling point on the 125k Baud is set to 87.5% (standard on CANopen and so on...). But in the case of the Bootloader of the STM32F105/7 I found out, that this standard sampling point isn't correct in every case and you get lots of frame errors or endless retransmissions of CAN messages.
The sampling point (and also the baudrate) is set in the BTR0BTR1 register of the PEAK PCAN dongle, well known as the TPCANBaudrate parameter in the CAN_Initialize method.
In my case, a sampling point at 50% has done the work!
I get the sampling point settings from the PCAN Viewer. If you connect in the viewer with a can dongle, you can change the baudrate settings,, by clicking on the arrow button next to the baudrate dropbox. There is a Bitrate-Settings window where you can create a new baudrate and then playing around with the prescaler, the first and second segment and also the syncronization width. By changing one of these settings the Bus-Timing-Register value (below the settings) is also changing. When you get the 50% sample point (in my case prescaler: 4, segm1: 7, segm2: 8 and sync:1) you have the needed value of the bus timing register (my case 0x0376).
All what you have to to now, is use this value as baudrate by casting it to TPCANBaudrate in the initialize method of the peak api: CAN_Initialize(Hande, (TPCANBaudrate)0x0376).
After that everything has worked for me and I never gets a frame error again.
Have a nice Day!
Alain
