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Asad
Joined: 02 Jul 2013
Posts: 1
Location: London
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| SPI Between PIC18f46k22 and PIC18F13K22 |
 Posted: Tue Jul 02, 2013 9:51 am |
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Hi All
I am new to this forum.
I trying to transfer 8 bit data from PIC18F46K22 to PIC18F13K22 using SPI Communication, both PIC have their own internal SPI hardware.
Master code
| Code: | #include <18F46K22.h>
#device ADC=8
#use delay(int=64Mhz)
int8 x;
void main()
{
setup_spi(SPI_MASTER | SPI_H_TO_L | SPI_XMIT_L_TO_H | SPI_CLK_DIV_4 );
setup_adc( ADC_CLOCK_INTERNAL );
SETUP_ADC_PORTS(sAN0|VSS_VDD);
while(1)
{
set_adc_channel( 0 );
delay_ms(20);
x = read_adc();
spi_write(x);
}
} |
slave code(PIC18f13k22)
| Code: | #include <18F13K22.h>
#use delay(clock=8M)
#use rs232(baud=9600, xmit=PIN_B7)//, rcv=PIN_B5, ERRORS)
void main(void)
{
setup_spi(spi_slave);
int8 x;
while(1)
{
x=spi_read();
printf("spi=%u\n\r",x);
}
} |
I want to send analog data from pic18f46k22 to pic18f13k22.
I Tested so many time the code, seem to build correctly but when tested in ISIS doesn't seem to work. SCK of master is not generating clock, SDO pin of master blink when the signal applied to AN0 changes. Slave (PIC18f13k22) should display analog values coming from master but this is displaying random data.
free screenshot |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Jul 02, 2013 10:24 am |
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| Quote: | | I Tested so many time the code, seem to build correctly but when tested in ISIS doesn't seem to work. |
You've just answered your own question.
Read what other forum users have to say about Proteus/ISIS.
Work with REAL hardware, then ask again, you will likely get help.
Mike |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19350
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| Posted: Wed Jul 03, 2013 1:19 am |
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Setup_spi, and #use SPI, are _different_, and _not always compatible_ commands. You should only use one or the other. Note in the manual, if you read 'setup_spi', it makes no mention at all of #use spi, and similarly #use spi, makes no mention of setup_spi.
Start by using one or the other.
Get rid of the #use spi in the slave device.
The slave needs to also have the clock edges specification.
setup_spi(SPI_SLAVE | SPI_H_TO_L | SPI_XMIT_L_TO_H);
Only 'master' specifies the clock rate, but the edges to use, need to be specified at both ends, and match.
I'd suggest dropping the clock rate. Though SPI is 'master clocked', with a slave PIC using just an 8MHz clock is a problem. Note that the SSP slave mode clock high time, and clock low time, are both specified at Tcy+20nSec. Tcy, is the instruction cycle time (just 2MHz on an 8Mhz clock.....). You need your SSP clock rate to be lower, with a slave PIC running just 1/8th the speed of the master chip....
Best Wishes |
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