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:
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