Labview embedded module for ARM - bidirectional IO Ports

[philip.holoch@sulzer.com]

I want to connect a Sensirion Sensor with a proprietary bus protocol to the Luminary 3S8962 Eval Board. The sensor should be connected to the same Pins as teh I2C interface. My main Problem now is, how do I configure a general purpose IO (i.e. GPIO-PB3) as bidirectional port? The slave sensor pulls the data line low to acknowledge the reception of the message. I have to read this into my VI. But when I configure the IO as output I cannot use it as input any longer.

Thanks for any help,

Philip

[TorbenPostel]

Hi Philip,

as far as I can see it, the GPIO ports cannot be configured as being biderectional ports. I have looked into the datasheet of the evaluation board and there it is written that they can be configured as input or output:

http://www.luminarymicro.com/index.php?option=com_remository&func=download&id=523&chk=869ea8c950d8cd31b7f729bcf52bbf9b&Itemid=591

In chapter 9.1.1.1 "Data Direction Operation" ( "General-Purpose Input/Outputs (GPIO) " ) it is written:

"The GPIO Direction (GPIODIR) register ... is used to configure each individual pin as an input and an output." 

Why do you think they can be used as bidirectional ports ? I think you have to change the direction programmatically or you have to use a second input in order to recognize the pulled down data line.

Regards,

Torben

Message Edited by TorbenP on 01-15-2009 07:49 AM

[philip.holoch@sulzer.com · Accepted solution]

Hello Torben,

that was my question, how can I program the pin direction. When I use a elemental node for a single pin, that is not possible as I understood it now because I can use a single pin either as input or as output in one VI. But I meanwhile found out, that if i use the whole port, it is possible to use an elemental I/O for input and another one for output in the same VI. This way I can "and" or "or" the bits to set and clear single pins and I can read them in the same VI.

Anyway, thanks for your effort,

Philip

[w0utje]

Go to tools > ARM tools > Elemental I/O wizard,

Load the target. (ex. Targets\Keil\Embedded\RealView\EK-LM3S8962\eio\eio.xml)

The resources are good, but they are attached to "pins".

this is just a reservation.

when you're on the page "Assign the pins to resources",

select your resource and remove the pin that is assigned. (ex. GPIO_IN_B4 and GPIO_OUT_B4)

Generate the stuff 2 pages further, restart LabVIEW et voila!

you can now use the GPIO_IN_B4 and GPIO_OUT_B4 at the same time.

try it with a LED.. but make sure you have enough time between the write and read of the pin (1000 ms or so..)

you see the result 🙂

[w0utje]

By the way, also manually set the io pins as input or output in an inline c-node before using them.

for the lm3s8962:

set as output:

GPIODirModeSet(GPIO_PORTC_BASE,GPIO_PIN_4|GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7,GPIO_DIR_MODE_OUT);
GPIODirModeSet(GPIO_PORTE_BASE,GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3,GPIO_DIR_MODE_OUT);

set as input:

GPIODirModeSet(GPIO_PORTC_BASE,GPIO_PIN_4|GPIO_PIN_5|GPIO_PIN_6|GPIO_PIN_7,GPIO_DIR_MODE_IN);
GPIODirModeSet(GPIO_PORTE_BASE,GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3,GPIO_DIR_MODE_IN);

use the port and pins you need..and also include the lm3sxxxx.h file to the inline c-node