AM335x ICE V2.1 DCAN -> Pin connection

Jim Schimpf

Hi,

I am trying to use the DB-9 on the ICE V2.1 and thus far have not connected to it. I am using the code from the dcanTxRX sample and have done this in the MUXING of the pins

/* Pin Mux for DCAN1 Tx Pin */
HWREG(SOC_CONTROL_REGS + CONTROL_CONF_UART_CTSN(0)) =
DCAN_SLEWFAST_RXDISABLED_PULLDWN_PUPDENABLED_MODE2;

/* Pin Mux for DCAN1 Rx Pin */
HWREG(SOC_CONTROL_REGS + CONTROL_CONF_UART_RTSN(0)) =
DCAN_SLEWFAST_RXENABLED_PULLUP_PUPDENABLED_MODE2;

This according to other posts should connect DCON1 to the UART0 pins. When I enable DCOM1 (or DCOM0) and do loop back I/O through them I do not get any voltage on CANH line of the DB-9. What else do I have to do. I saw some other posts about GPIO pin settings, is that what I have to do ?

The DCOM seems to work in loopback now I just have to connect to the outside world. The DCAN data in the AM335x technical manual seems self contained and doesn't reference how to connect to a pin. I could not find references about how to do this in the manual. In fact in the DCAN section they refer to the TIOC and RIOC registers which seem to control the muxing but these are not referenced in the dcanTxRx code.

Thanks for the help

--jim schimpf

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi Jim.

The CAN connector J9 is routed to the CAN0 pins that are pinmuxed on UART0_TX and UART0_RX. The ICE board schematics can be found at: http://processors.wiki.ti.com/index.php/AM335x_Industrial_Communications_Engine_Board_Design_Files

0 Jim Schimpf over 10 years ago in reply to Biser Gatchev-XID

Intellectual 745 points

Hi,

Thank you for the reply. I have not been able to find how you go from the schematic and the pin connection on the chip to setting up the mux to get the internal DCAN0 or 1 (I'm not fussy...) out on a particular pin. Is that information in the AM335x Technical Ref ? All I have to go on right now is the code listed above in the dcan.c from the Platform project.

--jim schimpf

0 Biser Gatchev-XID over 10 years ago in reply to Jim Schimpf

TI__Guru**** 393215 points

You should download the technical documents (Datasheet, Errata and Technical Reference Manual) from the AM335X product page. Pin modes for each I/O are listed in Table 4-1 from the datasheet.

0 Jim Schimpf over 10 years ago in reply to Biser Gatchev-XID

Intellectual 745 points

Thank you I have the DataSheet now and have table 4.1. Can you point me to a code example where this data is used to set up a mux ? I have all the values now but just don't know how to apply them.

Thank you for your patience.

--jim schimpf

0 Biser Gatchev-XID over 10 years ago in reply to Jim Schimpf

TI__Guru**** 393215 points

Sorry, I'm not a software expert.

0 Jim Schimpf over 10 years ago in reply to Biser Gatchev-XID

Intellectual 745 points

Thanks for your guidance thus far.

--jim schimpf

0 Jim Schimpf over 10 years ago in reply to Jim Schimpf

Intellectual 745 points

Hi,

The Data Sheet is what I needed it made sense of the code I had and I was able to get the MUX set up correctly with this code. The AM335x V2.1 board used UART0 connected to the DB-9 CAN connector. So I changed the platform dcan.c code to this function that lets me user either DCAN0 or DCAN1

/**
* @brief This function selects the DCAN pins for use. The DCAN pins
* are multiplexed with pins of other peripherals in the SoC
*
* @param instanceNum The DCAN instance to be used.
*
* @return TRUE/FALSE.
*
*/
unsigned int DCANPinMuxSetUp(unsigned int instanceNum)
{

switch( instanceNum )
{
case 0: // DCAN 0 (UART0)
/* Pin Mux for DCAN0 Tx Pin */
HWREG(SOC_CONTROL_REGS + CONTROL_CONF_UART_RXD(0)) =
DCAN_SLEWFAST_RXDISABLED_PULLDWN_PUPDENABLED_MODE2;

/* Pin Mux for DCAN0 Rx Pin */
HWREG(SOC_CONTROL_REGS + CONTROL_CONF_UART_TXD(0)) =
DCAN_SLEWFAST_RXENABLED_PULLUP_PUPDENABLED_MODE2;
break;

case 1: // DCAN 1 (UART0)
/* Pin Mux for DCAN0 Tx Pin */
HWREG(SOC_CONTROL_REGS + CONTROL_CONF_UART_CTSN(0)) =
DCAN_SLEWFAST_RXDISABLED_PULLDWN_PUPDENABLED_MODE2;

/* Pin Mux for DCAN0 Rx Pin */
HWREG(SOC_CONTROL_REGS + CONTROL_CONF_UART_RTSN(0)) =
DCAN_SLEWFAST_RXENABLED_PULLUP_PUPDENABLED_MODE2;
break;
}

return TRUE;
}

And it actually works. I have it sending a message to an Arduino with a CAN shield:

CAN RECEIVE PGM
Waiting CAN DATA

CAN_BUS GET DATA!

data len = 8
84 69 83 84 32 83 84 82

Thank you again for your invaluable help.

--jim schimpf

0 Biser Gatchev-XID over 10 years ago in reply to Jim Schimpf

TI__Guru**** 393215 points

Thanks for sharing this on the forum Jim!

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AM335x ICE V2.1 DCAN -> Pin connection