mesa 5i20 and DAC

Thank you PCW
I will send you all the information this weekend.

Hi PCW


I use the P2 connector of the 5i20 mesa board for the encoders and the P3 connector to command the DAC and the relays of my Maho milling machine.

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OUT_RLY_X: mesa 5i20 output, x relay, the main electric motor drives the x axis
OUT_RLY_Y: mesa 5i20 output, y relay, the main electric motor drives the y axis
OUT_RLY_Z: mesa 5i20 output, z relay, the main electric motor drives the z axis
OUT_RLY_FAST: mesa 5i20 output, fast motion relay
OUT_RLY_DIR: mesa 5i20 output, direction relay
OUT_RLY_AUTO: mesa 5i20 output, automatic mode relay
OUT_RLY_STOP: mesa 5i20 output, stop relay

IN_RAPID: mesa 5i20 input, MAHO user interface switch, FAST motion
IN_START: mesa 5i20 input, MAHO user interface switch, START
IN_STOP: mesa 5i20 input, MAHO user interface switch, emergency stop


DAC control

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D0-D7: mesa 5i20 output,data bus
MCDAC_MSB: mesa 5i20 output, select MSB or LSB
CS_MCDAC: mesa 5i20 output, chip select DAC

MCDAC_RDY: mesa 5i20 input, DAC ready for a new conversion


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t1-2: >50ns
t2-3: >50ns
t3-4: >900ns
t5-6: >900ns

The DAC (AD5570) has a bandwith of 20kHz, however I will use it at a frequency between 100 samples/sec up to 1ksps.

Cheers, Dom

OK thanks for the detailed info, that makes it easy!
Are you sure the LSB selector is high for LSB? Seems backwards
( though any output polarity errors can be fixed with the HM2 invert option)

Ill try and get you a test config tomorrow

You are right! It makes more sense if MSB is on the data bus when MSB/LSB is high!

Also RDY polarity must be reversed as well
because your buffer would be disabled during
the transfer if active high as shown in the chart

The DAC is not directly accessible by the mesa board. The DAC is controlled via SPI by a micro-controller I will program.
As I was focused on designing the hardware, I brewed this temporary protocol however I agree with you about using standard hand-shaking protocol.