One task for telemetry is generating tones. Sparkfun sells a AD9837 based DDS tone generator. This blog describes how to interface this board with a beaglebone. Eventually, I intend to set up a cheaper chip.
The AD9837 requires SPI communication. So, time to figure out SPI. I have used i2c, so hopefully they’re similar.
Some internet resources:
basic spi tests (pocket beagle library)
From the AD9837 data sheet
“To inform the AD9837 that the contents of the control register will be altered, Bit D15 and Bit D14 must be set to 0 …”
The AD9837 seems to be write only.
On the Beaglebone, SPI0 has the following pins:
SDATA is MOSI (P9-21)
FSYNC is CS (P9-17)
SCLK is SCK (P9-22)
MISO (P9-18) – not used for AD9837