I am controlling the ADC via SPI. Fill, Dump, readout, configuration settings etc. works like a charm.
However, now I want to initate a fill using the FILL+- pins which does not yet work (FIFO status remains emtpy, does not fill). I think I do not understand the datasheet and therefore I would be glad if someone "fills" me in ;)
- What signal does the ADC expect at the FILL+ and FILL- pins which provokes a filling of the FIFO? What signal at the FILL+ and FILL- pin do I need to apply to trigger a fill?
According to the datasheet "[...] the user initiates a capture by driving the FILL+- pins high [...]" or by "[...] asserting the differential FILL+- pins [...]". And that is the part I do not understand. Since FILL+ and FILL- are complementary pins, does the ADC expect FILL+ = +1.8 V and FILL- = -1.8 V? Or should both pins be driven logic high that is FILL+ = +1.8 V, FILL- = +1.8 V?
- What about the timing? Should both pins the pulled high or low simultaneously? Or one after another? If the latter, are there any timing requirements I need to meet?
My sequence is the following:
- Power up ADC.
- Perform a soft reset.
- Put the ADC in single capture mode by writing the FIFO fill mode bits in the fill control register (0x101, 0).
- Trigger fill using FILL+- pins by pulling both FILL+ and FILL- to +1.8 V. (that where I am stuck, FIFO does not fill!)
Thank you in advance for your help.
[edited by: SB235 at 10:41 AM (GMT -5) on 3 Feb 2021]