Releasing the DO output from the SD in TAQOZ

Peter JakackiPeter Jakacki Posts: 8,641
edited 2019-02-21 - 04:03:07 in Propeller 2
Here's some information about the SD DO line that stays enabled regardless of the SD chip select.
It needs at least one clock after the chip select goes high with DI high. Here I issue a CMD0 just to activate the DO etc and then release the DO.
TAQOZ# 0 0 CMD . --- 1 ok
TAQOZ# 60 HIGH 61 HIGH 61 LOW  --- ok
Normally I supply 8 clocks for the SD card but a single clock is all it needs to release the output.
60 HIGH takes the SD chip select high
61 HIGH is the SD clock
Usually DI is left high anyway but you can do a 59 HIGH if you want to make sure.

My scope shows the DO floating to the midpoint where I have placed 100k to 3.3V and 100k to ground bias network for this test. (MOSI and MISO labels are swapped)


This is the new TAQOZ running in the FPGA image at 20MHz
  Parallax P2  .:.:--TAQOZ--:.:.  V1.1--v33h         190219-1900

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