Power Up Configuration of U0RTS and U1RTS (MOD5234)

[rkramer_de]

Hello,
according the MC5234 documentation, the U0RTS (Pin 38) and U1RTS (Pin 23) should be configured as GPIO Inputs.

Unfortunately, these lines are driven high shortly after power up of the MOD 5234 and then they are enabling the driver of a RS485 Half-Duplex bus. As an result, the bus is blocked.

Is there any configuration option available to avoid this behaviour?

Kind regards

Reinhard

[Ridgeglider]

Take a look at c:/nburn/MOD5234/include/pinconstant.h

J2[23] and J2[38] can be configured several ways. I think the default pin configuration is for use with the serial ports.

To use them as GPIO, there are two considerations: In software, you can reconfigure them using:
J2[23].function(PINJ2_23_GPIO);
J2[38].function(PINJ2_38_GPIO);

Next, if you are using one of the dev boards, make sure there is not a jumper or hard connection tying either pin to something in conflict. Nothing on the module itself prohibits using these pins as GPIO.

[rkramer_de]

I think the default pin configuration is for use with the serial ports.

This is exactly the problem. From powerup, these lines should be GPIO (Freescale documentation).
Then these lines are configured from the boot code as outputs in high state. Then the system wait 2 seconds until the start of my user programm. Therefore the bus is blocked for two seconds.
Is there any chance to avoid this programming during booting the MOD5234?

Kind regards

Reinhard

[Ridgeglider]

Got it. Not sure this is possible w/o changing the monitor. I know you can setup some of the default COM params in the monitor, like setting baud rate or changing the default debug monitor from COM0 to COM1, but I don't think there's a way to default these pins to gpio. Sounds like a question for larry or paul...

[rnixon]

I think only uart0 should be active so the boot monitor will work, unless you change the boot monitor to uart1. Are you sure RTS is being driven and its not that you need a pull up/down on your h/w?

[rkramer_de]

I have tested the behaviour with the development board and pull down resistors. The first RTS is activated 1.3ms after power up, the second one is activated about 500us later. I have checked it with an oscilloscope.