Post by thread:[PIC]: 16F877 > MSSP >SPI >AD7715

Hello PIC.ers, Is there anyone out there in PICland who has -successfully- used the MSSP in SPI mode to communicate with an Analog Devices AD7715 adc? Tony Kubek has a note in the PIC archives about talking MSSP>SPI to the related AD7730. His source code looks nice & well encapsulated but unfortunately he does not elaborate on the AD_SEND_BYTE routine he invokes to do both a byte write & read together. (Tony, if you're listening...?) The 7730 is a part I played with a while back but dropped it in favour of the 7715 -it's cheaper & more available here. IIRC the 7730 registers are all byte-wide & this lends itself to MSSP SPI comms. where the port wants to deal in 8bit words only. The 7715 transmits its 16bit adc data as a complete word, with no choice in the matter. It doesn't look like the SSPSTAT,BF flag can be setup to trip on incoming 16bit words, only 8bit. Given the above, *and* : (a) I'm already communicating I2C on the *same* bus lines of the MSSP. (no problems there) (b) I Must watch my TMR0 ISR Ps&Qs while I'm about all this. erm... would it be a collective opinion out there that I give up using the MSSP SPI and rather go to bit-banging the SPI on some other I/O pins? It feels that way right now. best regards, John e-mail from the desk of John Sanderson, JS Controls. Snailmail: PO Box 1887, Boksburg 1460, Rep. of South Africa. Tel/fax: Johannesburg 893 4154 Cellphone no: 082 741 6275 email: spam_OUTjsandTakeThisOuTpixie.co.za Manufacturer & purveyor of laboratory force testing apparatus, and related products and services. -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu

Hi John, the SPI module sends the SCLK clock to AD7714 and synchronizes this way the transfer of 16-bit data. So you can use unsigned char SPI(unsigned char TX_Data) ( SSPBUF = TX_Data; // start clock and send data while(BF == 0) // wait until new data ready ; return(SSPBUF); // return new 8-bit data ) main() { Data_1 = SPI(0xFF); Data_2 = SPI(0xFF); } Andrej _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu