GPIOTE Tasks

[Timur Beganovic]

How many GPIOTE Tasks can I use at the same time. I want to drive six different pins with six different tasks which are connected to three events. Each event generates two tasks.  
Although I am using different channels for each task I can only assign four tasks
because of:  __O  uint32_t  TASKS_OUT[4];  

NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0];

Is the task number really limited to four tasks?
 
best regards

[ovrebekk]

Hi 

The GPIOTE module in the nRF51 series only has 4 channels, that is correct. This limits you to controlling 4 pins at the time through the GPIOTE. 

In the nRF52832 and nRF52840 devices this has been increased to 8. 

Best regards
Torbjørn

[Timur Beganovic]

Thank you Torbjørn.

I just need to mirror the signal from the output pin A (which is timer event driven signal) to the output pin B? Is there any way to achieve this?

[ovrebekk]

Hi

Yes, you should be able to set up a GPIOTE input channel on output pin A and connect that to a GPIOTE output channel on bin B over the PPI. 

If you configure both GPIOTE channels in TOGGLE mode you get away with only two GPIOTE channels, but you have to take care to avoid output pin B being inverted compared to pin A. 

An alternative approach is to use two GPIOTE input channels, in HITOLO and LOTOHI mode respectively, and connect them to the CLEAR and SET tasks of the GPIOTE output channel. This will remove the risk of inverting the output, but will require one more GPIOTE channel and one more PPI channel. 

Best regards
Torbjørn

[Timur Beganovic]

Thank you for the explanation, Still, it doesn't solve my problem. I already used 3 GPIOTE channels to control 3 pins. The GPIOTEs generate tasks based on timer events (PWM). In order to mirror these 3 pins to another 3 pins I will need 3 additional GPIOTE channels, right? That would be 6 GPIOTE channels altogether.

best regards

[ovrebekk]

Hi 

You are correct. The nRF51 doesn't allow you to control more than 4 pins through the GPIOTE. 

If the pins are supposed to be the same couldn't you just interconnect them externally on your PCB?

Best regards
Torbjørn