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Martin Land
Joined: 09 Sep 2009
Posts: 2
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| MCP2515 PICtail Plus Daughter Board with Explorer 16 |
 Posted: Wed Sep 09, 2009 3:40 am |
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Hello,
I have a problem with setting up a communication with the MCP2515. For testing I use the source-code from the file can-mcp251xx.c.
The hardware SPI pins are set with the following code.
| Code: | #ifndef EXT_CAN_CS
#define EXT_CAN_CS PIN_B5
#define EXT_CAN_SI PIN_F8
#define EXT_CAN_SO PIN_F7
#define EXT_CAN_SCK PIN_F6 |
The problem is when the function can_set_mode is called there is no result (no communication?). It is hanging in the while-loop.
| Code: | void can_set_mode(CAN_OP_MODE mode) {
struct struct_CANCTRL old_CANCTRL;
old_CANCTRL=mcp2510_read(CANCTRL);
old_CANCTRL.reqop=mode;
mcp2510_write(CANCTRL, (int)old_CANCTRL);
do {
old_CANCTRL=mcp2510_read(CANCTRL);
} while (old_CANCTRL.reqop != mode);
} |
| Code: | int mcp2510_read(int address) {
int command[2];
int i;
int data;
command[1]=0x03;
command[0]=address;
output_low(EXT_CAN_CS);
for (i=0;i<16;i++) {
output_bit(EXT_CAN_SI, shift_left(&command[0],2,0));
output_high(EXT_CAN_SCK);
output_low(EXT_CAN_SCK);
}
for (i=0;i<8;i++) {
shift_left(&data,1,input(EXT_CAN_SO));
output_high(EXT_CAN_SCK);
output_low(EXT_CAN_SCK);
}
output_high(EXT_CAN_CS);
return(data);
} |
| Code: | void mcp2510_write(int address, int data) {
int command[3];
int i;
command[2]=0x02;
command[1]=address;
command[0]=data;
output_low(EXT_CAN_CS);
for (i=0;i<24;i++) {
output_bit(EXT_CAN_SI, shift_left(&command[0],3,0));
output_high(EXT_CAN_SCK);
output_low(EXT_CAN_SCK);
}
output_high(EXT_CAN_CS);
} |
Any help or insides would be greatly appreciated.
Regards,
Martin Land. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Sep 09, 2009 1:24 pm |
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What PIC are you using on the Explorer16 ?
What is your CCS compiler version ? |
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Martin Land
Joined: 09 Sep 2009
Posts: 2
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| Posted: Thu Sep 10, 2009 1:10 am |
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Hello.
I am using the PIC24FJ128GA010 with a PCD compiler, version 4.093. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 10, 2009 1:29 pm |
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I think the problem may be caused by the different size of the 'int'
data type in PCD, compared to PCM or PCH.
In PCD, an 'int' is a signed 16-bit integer. (i.e., ANSII compatible)
But in PCM or PCH, an 'int' is an unsigned 8-bit integer.
The mcp-251x.c driver is written for PCM or PCH. This is going to cause
problems. For example, the shift_left() routine operates on bytes.
In mcp2510_read(), the command[] array is assumed to be an array of
bytes. But in PCD, it becomes an array of signed 16-bit integers.
The shift_left() routine won't work correctly now.
I don't own the PCD compiler. Maybe someone who has it can tell you
how to make it be compatible with the CCS drivers. Maybe there is a
quick fix. |
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bkamen
Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA
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| Posted: Fri Sep 11, 2009 8:19 am |
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I do --- but I think you can typedef the int's into int8's if the rest of your code is int8 happy...
I'd have to look more closely later tomorrow...
-Ben
_________________
Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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