Invert Port at a NRF51822

[Bitschubse]

Hello,

I already searched the forum, but I didn't find anything.

Is there a way to invert a port on a NRF51822?

I use this chip together with an XMega-Chip and they communicate via uart. At the XMega, the TX-Pin is inverted, because it is also used to communicate via a led, but the led should not light up all the time. At the xmega I am able to invert a port signal, for in- and output. Is there a configuration option for the nrf? I didn't find anything.

Thanks for your help.

[JohnBrown]

Can't you simply connect the other end of the LED to the other rail?

[Bitschubse]

Sorry, there is no way to put the LED to the other rail. I already considered that.

[MartinBL]

I don't think I understand what it is you want to do. Is the LED connected to the UART TX line? And you want to light up only when transmitting? Or do you simply want to connect an LED to an nRF51 pin and turn the LED on and off?

[Bitschubse]

The LED is connected to the UART TX line and I want it to light up only when transmitting. I tried to only switch on the TX line, when transmitting. That works, but is still too much light, even if I use 1MBaud. That's because I have to wait some time before and after sending, because I don't want to run into frame errors for the first and last byte. Is there no software configuration like on an atmel chip, which says, that this port pin is inverted?

[JohnBrown]

I think the simple answer is no. I certainly haven't come across any such feature. I'm guessing that someone at Nordic would have replied in the affirmative by now if such a feature existed. There might be some convoluted way to use the PPI system, but even if that worked, it would be a total botch.