STM32F4 CAN bootloader, use CAN1 AND CAN2 in parallel (TX)?

[friedrich.janus]

Hello Community,

Product in question is STM32F446.

I am trying to prepare the use of bootloader over CAN. the follwing questions occur:

a) The bootloader is specified using CAN2 only. So when using the CAN1 for the product you cannot help but to wire CAN2 parallel to CAN1 in order to use it for the bootloader. Is there any way to use CAN1 only?

b) According to specification an external HSE source 4MHz ... 28MHz is required for the CAN bootloader. Are there any required tolerances for the crystal? Would a 0,5% resonator do?

rgds

[friedrich.janus]

Let me rephrase this:

Given is:

A product that shall use CAN1 as main communication interface.

The product uses an external crystal for the clock generation that is sufficient accurate enough for a stable CAN communication. The product shall be updateable through the CAN interface via the MPU internal bootloader.

If you want to use CAN as interface for the bootloader you have to use CAN2. The product also uses CAN1.

Q: Is the bootloader written in such a way that allows the parallel connection of CAN1 and CAN2 (especially TX) to one tranceiver? Means: Does the bootloader disable the CAN1 TX pin (float) when using CAN2? Or is it necessary to have a separate interface to CAN2?

rgds

Friedrich

[friedrich.janus]

PUSH

Can anyone please have a look on the topic: CAN Bootloader

rgds