Using SPI and Maxim 5354 DAC

[slahiri]

<font face="Courier New" size=-1>Guys,
I am using 16F877 to connect Maxim 5354 "DAC" through SPI. I need to send 1v using two byte.I am sending the value but seeing the voltage ramping up to 3v at the DAC output. This is what I wrote, can some one take look at it and tell me what I am doing wrong.

Thanks

setup_spi(SPI_MASTER |SPI_L_TO_H |SPI_CLK_DIV_16);
delay_us(30);
if (choice==1 || choice==2)
{
full_charge=6;
output_low (PIN_C0);
spi_write(32);
spi_write(8);
delay_us(30);
spi_write(64);
spi_write(0);
delay_us(30);
output_high(PIN_C0);
delay_us(30);</font>
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This message was ported from CCS's old forum
Original Post ID: 13002

[Charlie U]

:=<font face="Courier New" size=-1>Guys,
:= I am using 16F877 to connect Maxim 5354 "DAC" through SPI. I need to send 1v using two byte.I am sending the value but seeing the voltage ramping up to 3v at the DAC output. This is what I wrote, can some one take look at it and tell me what I am doing wrong.
:=
:=Thanks
:=
:= setup_spi(SPI_MASTER |SPI_L_TO_H |SPI_CLK_DIV_16);
:= delay_us(30);
:= if (choice==1 || choice==2)
:= {
:= full_charge=6;
:= output_low (PIN_C0);
:= spi_write(32);
:= spi_write(8);
:= delay_us(30);
:= spi_write(64);
:= spi_write(0);
:= delay_us(30);
:= output_high(PIN_C0);
:= delay_us(30);</font>

I checked the device you are using, and it appears that it requires SPI mode 0,0 which is not possible with the basic spi setup above. Follow the link below and the links in the various messages for a full explanation of the problem.

CCS changed the SPI setup when they released version 3.xxx and the basic parameters no longer create either mode 0,0 or 1,1 which most devices use.

A good reference for SPI is a Motorola applications note AN991/D.
___________________________
This message was ported from CCS's old forum
Original Post ID: 13043