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Part Number: ADS7950
According to ADS7950 datasheet, 4 GPIO pins can be configured as general purpose I or O. But the customer writes 0x400c to the register (GPIO3 is configured as output); then writes 0x1818 to the register (Manual Mode + GPIO3 output is 1), the ADS7950 has no response. What reason is this? Could you give some advice?
Best Regards, Amy Luo
The command 0x1818 seems to be correct to sample channel 0 and set GPIO3 high.
I predict this means that the GPIO was likely not set correctly. Section 8.5.2 GPIO registers of the datasheet explain show to do this.
I suggest trying the following:
0x4200h this will reset all the GPIO register settings
0x4008h this will set GPIO3 as output
Also remember that this device has a 2 cycle delay. meaning that in FramenN you set GPIO3 high, but you will not see it until Frame n+2.
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In reply to Cynthia:
We send 0x4200 as you said, then send 0x4008/0x400C, then send 0x1818, but GPIO3 still dosen't work....
In reply to user5278687:
There is no sample code available
Would you share a scope shot with the digital lines probed on the oscilloscope?
This will about 6 frames, the first half to set the GPIO, and the second to get the conversion data, as it take 2 frames after the initial conversion for valid data out.
Be sure to use a known DC input at the ADC input to be able to compare expected vs actual
This will help verify timing as well as the digital lines showing correct communications
So glad to hear!
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