How CANBUS transmission speed is set to 5 kb/s?

[nnnnff]

CANbus transmission speed in macro Settings are: 125 KB/s, 250 KB/s, 500 KB/s, 1000 KB/s.
Now I want other transmission speed, such as: 5 KB/s.
How should I do? Help me!thank you.

[LeighM]

What hardware are you using?
e.g. External CAN controller such as MCP2515 or a processor with internal CAN, if so, which one?

[nnnnff]

I use the MCP2515.
How should I do? thank you.

[LeighM]

Have a look at the MCP2515 data sheet and the configuration registers CNF1, CNF2 and CNF3 and then you could customise the Init code of the CAN component.

Code: Select all

	%a_SPI_Master_Byte(%a_CNF3_VAL);         	// CNF3      0x28
	%a_SPI_Master_Byte(%a_CNF2_VAL);         	// CNF2      0x29
	%a_SPI_Master_Byte(%a_CNF1_VAL);         	// CNF1      0x2A

Change to some new values, e.g. as follows

Code: Select all

	%a_SPI_Master_Byte(0x07);         	// CNF3      0x28
	%a_SPI_Master_Byte(0xff);         	// CNF2      0x29
	%a_SPI_Master_Byte(0x27);         	// CNF1      0x2A

Having had a quick look I think the example above would give a CAN bit rate of 10kb/s
I don’t think you will be able to get down to 5kb/s with a 20MHz clock, you might have to change that too.

[nnnnff]

Have a look at the MCP2515 data sheet and the configuration registers CNF1, CNF2 and CNF3 and then you could customise the Init code of the CAN component.

Code: Select all

	%a_SPI_Master_Byte(%a_CNF3_VAL);         	// CNF3      0x28
	%a_SPI_Master_Byte(%a_CNF2_VAL);         	// CNF2      0x29
	%a_SPI_Master_Byte(%a_CNF1_VAL);         	// CNF1      0x2A

Change to some new values, e.g. as follows

Code: Select all

	%a_SPI_Master_Byte(0x07);         	// CNF3      0x28
	%a_SPI_Master_Byte(0xff);         	// CNF2      0x29
	%a_SPI_Master_Byte(0x27);         	// CNF1      0x2A

Having had a quick look I think the example above would give a CAN bit rate of 10kb/s
I don’t think you will be able to get down to 5kb/s with a 20MHz clock, you might have to change that too.