Arduino SPI w/ two slave devices

hi,

i working on project uses 12-bit adc (intersil isl26321) , 10-bit dac (microchip mcp4911), both on spi interface. have written code interface w/ both devices independently works fine have run problem when combining 2 pieces of software interface both devices in sequence.

i have written subroutines communicating w/ both devices there sort of "cross talk" between them resulting in corrupt data to/from both devices.

the code written returns adc values between 0 , 3 on serial monitor when result should 1000 (1v using 4.096v reference). oscilloscope confirms there no data returned adc. clock , cs both appear correct.

if comment out 2 spi.transfers in lp_bias(), adc results correct.

if leave spi.transfers in , instead comment out call lp_bias(i) in loop, results 2.5 times higher should be. oscilloscope confirms data line returning larger number should. clock , cs still correct.

the swept voltage produced dac appears noisy when adc code included.

i appreciate if @ attached code , give me hint doing wrong.

thank you,
greg

first of all, stop stupid texting , write full words please.

second, why mix normal port functions direct port manipulation?

third, can post schematic? both have separate cs/ss?

and timing critical need mix asm nop commands?

Arduino Forum > Using Arduino > Programming Questions > Arduino SPI w/ two slave devices

arduino