CAN - Flash Documentation

For detailed explanation of concepts see this document

Terminology

Term	Explanation
BOOT_ADD0 & BOOT_ADD1	An option byte (programmable setting) ; set in STM32 Cube Programmer
Boot Pin	A hardware pin on the STM32F767ZI ; controls which memory area to boot into
STM32 Cube Programmer	An application which allows the flashing, and memory manipulation of STM32 MCU’s
System Bootloader	A bootloader made by STM located at memory address: 0x0100 0000. Enables flashing the MCU via CAN, UART, SPI and more…

Setup

1. Boot Option Bytes:

   1. There are two option bytes relevant to CAN Flash, these are BOOT_ADD0 and BOOT_ADD1
   2. Set BOOT_ADD0 to value 0x80 (address 0x00200000), and BOOT_ADD1 to value 0x40 (address 0x00100000) in Option Bytes of STM32CubeProgrammer. If option byte values are already configured as such, leave as is. See Figure 1 to see different boot addresses
   3. These options bytes are chosen by the firmware on reset via the boot pin. If the boot pin is LOW, BOOT_ADD0 is chosen and vice versa.
   4. Verify:
      1. Tie the boot pin to high ; choose BOOT_ADD1
      2. In STM32 Cube Programmer: go into MCU Core tab > press any reset option
      3. In STM32 Cube Programmer: go into MCU Core tab > press run and then halt
      4. In STM32 Cube Programmer: go into MCU Core tab > check if the LR ( instruction pointer ) register is in the memory range of 0x1FFX XXXX
      5. If so, the MCU is currently in system bootloader

2. Read/Write protection option bytes:

   1. While BOOT_ADD0 and BOOT_ADD1 are the most important, other option bytes must be left in their DEFAULT to enable reading and writing to flash memory
   2. These are the write protection option bytes: nWRP# and read protection option byte: RDP
   3. Ensure all these option bytes are left as their default configuration. See Figure 2 for default option bytes.
   4. For RDP: DO NOT CHANGE IT TO CC (Level 3 Protection) → DEBUG OPTIONS WILL BE DISABLED FOREVER
   5. Verify:
      1. Check with Figure 2
      2. In STM32 Cube Programmer : go into Erasing & Programming tab > do a full chip erase for flash memory
      3. If it doesn’t work, your read/write protections are set wrong

3. Can-prog download, and raspberry pi setup:

   1. In order to program the STM32 MCU with can-prog you will need a computer with a CAN interface → in testing we used a raspberry pi with a CAN Hat for our CAN bus setup
   2. For flashing with CAN we will need a bitrate of 125000 for our CAN network
   3. Using ifconfig you can check which networks are set up on your system → you should see either can0 or can1 ; either is fine to use, we will use can1
   4. Verify:
      1. Using ip -details -statistics link show can1 ; see if the CAN network is configured at the required bitrate of 125000. If so, skip the steps below
      2. Using sudo ip link set can1 down ; pull the CAN network down
      3. Using sudo ip link set can1 type can bitrate 125000 ; configure the CAN network to use the required bitrate of 125000
      4. Using sudo ip link set can1 up ; bring the CAN network up again
   5. Git clone this repo’s version of can-prog and install

4. CAN - 2 Wiring, BOOT pin setup and CAN Transceiver:

   1. You will need a CAN transceiver for the STM32. We require the CAN-2 interface on the STM32, specifically pins PB_5 for CAN_RX and PB_13 for CAN_TX.
   2. Drive BOOT pin high (See Figure 3)
   3. Connect the CAN bus by connecting CAN2_RD from PB_5 and CAN2_TD from PB_13 into CAN_RX and CAN_TX on the CAN transceiver. Note that there are other CAN2_RD and CAN2_TD pins, but it must be from PB_5 and PB_13. Also note that there are multiple PB_5 and PB_13 pins, and that PB_5 and PB_13 must be connected to the ones in Figure 4.a OR Figure 4.b, but must not be combined (i.e. do not connect PB_5 from Figure 4.a, and PB_13 from Figure 4.b)

Procedure

1. Write the binary to the board
   1. i.e canprog -n can0 -f bin stm32 write [file_name] -a 0x08000000
      1. -n → interface name
      2. -f → file format (hex, bin)
      3. -a → address to write → default is 0x0800 0000 DON’T CHANGE
      4. [file_name] → file to write
2. Run the flashed application
   1. i.e canprog -n can0 stm32 go -a 0x08000000

Additional Notes

1. Unlock, lock, and speed commands with can-prog tool are not necessary
   1. The unlock and lock commands change the readout protection and option bytes ; in our use case we do not need to lock the chip after flashing → therefore do not use
   2. The speed command changes the bitrate of the CAN-2 interface on the STM32, however the default is already set correctly upon system reset → therefore do not use

Appendix

Figure 1

Figure 2

Figure 3

Figure 4.a

Figure 4.b