[#5636] generic gpio works on bf533 in the opposite way

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[#5636] generic gpio works on bf533 in the opposite way

Submitted By: Mingquan Pan

Open Date

2009-10-23 00:30:30     Close Date

2009-10-26 03:34:34

Priority:

Medium     Assignee:

Michael Hennerich

Status:

Closed     Fixed In Release:

N/A

Found In Release:

2010R1     Release:

Category:

N/A     Board:

N/A

Processor:

BF533     Silicon Revision:

Is this bug repeatable?:

Yes     Resolution:

Rejected

Uboot version or rev.:

    Toolchain version or rev.:

09r1-rc9

App binary format:

N/A     

Summary: generic gpio works on bf533 in the opposite way

Details:

 

generic gpio works on bf533 in the opposite way.

 

When testing led1, given 1, turn off and given 0 ,it is on.

 

root:/sys/devices/virtual/gpio/gpio2> echo out > direction

root:/sys/devices/virtual/gpio/gpio2> echo 1 > value

root:/sys/devices/virtual/gpio/gpio2> echo 0 > value

root:/sys/devices/virtual/gpio/gpio2> echo 1 > value

 

when testing btn1, pushing is 0 and release is 1.

 

root:/sys/devices/virtual/gpio/gpio5> echo in > direction

root:/sys/devices/virtual/gpio/gpio5> cat value

1

root:/sys/devices/virtual/gpio/gpio5> cat value

0

root:/sys/devices/virtual/gpio/gpio5> cat value

 

 

Follow-ups

 

--- Mike Frysinger                                           2009-10-23 02:29:27

and you're using 2009R1+ u-boot right ?

 

--- Michael Hennerich                                        2009-10-23 03:53:14

This is absolutely expected behavior. It's due to the way the LEDs and Buttons

are wired on the BF533-STAMP board. The button has a PULL-UP, while the button

press shorts the PULL-UP to GND. So pressing the button is Logic 0 while open is

Logic 1.

With the LEDs it's quite similar - the Anode of the LED is permanently

connected to the Positive Supply - while a logic Zero connects the Cathode to

GND - and thus turns on the LED.

 

Rejected

 

--- Mingquan Pan                                             2009-10-26 03:34:34

Well, but I don't remember that when testing simple gpio case, the reaction of

bf533 stamp is on the opposite of other boards. So I have to treat it

differently in the generic gpio test case. Close.

 

--- Mike Frysinger                                           2009-10-26 04:03:34

i think i added workarounds to the simple gpio userland code

 

 

 

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