ben-blinkenlights/ubbctl/README

ubbctl - Control UBB signals
============================

ubbctl queries the state of UBB signals and allows the user to change
them. It can run in parallel with any other UBB users.


Querying
--------

To query the UBB signals, run

# ubbctl

This will display something like this:

nPWR=1 DAT2=F1 DAT3=F1 CMD=F1 CLK=Z1 DAT0=1 DAT1=0

"0" means that the pin is driven low. "1" means that is it driven
high. If the pin reads back as something different than what it is
set to, this is indicated as "0!1" (pin is shorted to VDD) or "0!0"
(pin is shorted to ground).

"Z0" and "Z1" means that the pin is an input without internal
pull-up (note however that all pins but nPWR and CLK) have external
10 kOhm pull-ups) and that it reads back a low or high,
respectively.

"R0" and "R1" are like "Z0" and "Z1", except that the internal
pull-up is enabled.

"F0" and "F1" indicate that the pin configured as a function (i.e.,
for the MMC controller) and does not operate as GPIO.

ubbctl can run in continuous mode, in which it updates the status
regularly (currently every 200 ms):

# ubbctl -c

To exit continuous mode kill the process, e.g., which Ctrl-C.


Setting
-------

ubbctl can change the configuration of the UBB pins. The syntax is
the same as the one used for the status display except that there
are no readback values. E.g., nPWR=1 would disable power, CLK=R
would configure CLK as input with pull-up, etc.

A pin can be changed several times. For example, if the idle state
of DAT0 is 0

# ubbctl dat0=0

then

# ubbctl dat0=1 dat0=0

would send a short positive pulse.

ubbctl also recognizes the keywords ON and OFF to control power to
the 8:10 interface. They're synonymous to nPWR=0 and nPWR=1,
respectively.