CAN 1 GPIO configuration

p070042 · ‎05-07-2018

Hi,

I am working on CAN1 module & would like to configure out its GPIO as input & output. I have following confusion.

In Special cases of IBE and OBE of excel sheet of MPC5748G, it is written as

CAN_TX pin "always ON"

CAN_RX pin "SIUL2_MSCR"

So, Is it menas, There is no need to configure CAN_TX pin because it is always ON?

Now below shown configurations are taken from Excel sheet of MPC5748G, It states that for there is need to write value 6 in Source signal select and Also IMCR value as[701-512] which is also 6 in input muxing table.

Can you please guide me how I can configure these two pins to work CAN_1 good? Special cases are confusing me? In which situation I need to take care about special case?

PJ[15]

701

0000_0110

CAN1RX

FlexCAN_1

I

PJ[14]

0000_0001

CAN1TX

FlexCAN_1

O

FlexCAN_1	CAN1RX	189	0000_0000	-	disable_low
			0000_0001	IO_PAD	PA[0]
			0000_0010	IO_PAD	PC[3]
			0000_0011	IO_PAD	PC[11]
			0000_0100	IO_PAD	PF[15]
			0000_0101	IO_PAD	PJ[13]
			0000_0110	IO_PAD	PJ[15]
			0000_0111	IO_PAD	PN[12]

PetrS · ‎05-09-2018

Hi,

the note means you do not need to set the MSCR[OBE] bit for the TX pin, just select the function.

If you would like to use CAN1 on pins PJ14/PJ15 the setting should be

/* configure CAN1TX and CAN1RX pin functions */

SIUL2.MSCR[158].B.SSS = 1; /* Pad PJ14: Source signal is CAN1_TX */

SIUL2.MSCR[158].B.SRC = 3; /* Pad PJ14: Maximum slew rate */

SIUL2.MSCR[159].B.IBE = 1; /* Pad PJ15: Enable pad for input - CAN1_RX */

SIUL2.IMCR[701-512].B.SSS = 6; /* CAN1_RX : connected to pad PJ15 */

BR, Petr

p070042 · ‎05-09-2018

Hi,

Thanks its really helpful,

I am confused with special case of IBE and OBE, It is written for PJ15 that its input is controlled through SIUL2 module. In what case I need to check special case of OBE and IBE, or do I need to always consider special cases?

PetrS · ‎05-09-2018

Hi,

“special cases” just tells if the user have to set OBE/IBE or not for particular pin fuctions.

So it is recommended to check this “special cases” tab.

But if you set the OBE or IBE, even it is not needed, nothing happens.

BR, Petr