nRF52832 one of output (p0.15) lost its power

RE: nRF52832 one of output (p0.15) lost its power

ovrebekk — Mon, 15 May 2017 10:11:20 GMT

I had to check with the hardware guys. Apparently this is the typical sink current when you pull the GPIO down in standard drive, as the voltage applied to the pin (the pad voltage) changes. In other words this is not the same as the source current when you set the GPIO high (this current is typically lower).

RE: nRF52832 one of output (p0.15) lost its power

Damian — Fri, 12 May 2017 09:57:07 GMT

Yes, table states 1-2-4 mA but I mean figure 23 on page 155 in specification where can you read around 6 mA. So how should I interpret values in this figure?

RE: nRF52832 one of output (p0.15) lost its power

ovrebekk — Thu, 11 May 2017 12:22:00 GMT

Hi Damian

6 mA in standard drive? As I read the table it supports 1-2-4 mA in standard drive (min-typ-max), and 6-10-15 mA in high drive (when VDD >= 2.7V).

I have to get back to you on the min, typical, max definition, but I believe it is an approximate representation of the 3 sigma deviation (meaning 99.7% of devices should be within the min and max values). Once I can double check this with the hardware guys I will get back to you.

RE: nRF52832 one of output (p0.15) lost its power

Damian — Mon, 08 May 2017 06:39:40 GMT

In my case there is 2,72 mA for all two LEDs - total current draw from pin, measured, not calculated. According to nRF52832 Product Specification v1.3 on p. 155 figure 23, when I supply my nRF with 3,3 V the GPIO drive strength can be a little bit more than 6 mA in standard drive. Likewise on the same page in table there was written 4 mA in standard mode when VDD >= 1,7 V. This is slightly misleading when I taking into account what you written @Torbjørn Øvrebekk. Could you define the terms: min, typical and max?

RE: nRF52832 one of output (p0.15) lost its power

ovrebekk — Wed, 03 May 2017 12:04:06 GMT

As mentioned by others you should set the GPIO in high drive mode, if you need to draw as much as 2,7mA from it.

In standard drive mode the pins are only ratified to 1mA minimum, 2mA typical, and if you go outside these values you are in untested waters ;)

Also, you can typically sink more current than you can source (in other words, you should draw the pin low and have current flowing into it, for maximum current).

Please keep in mind that you can only have 3 pins in high drive mode at the time.

RE: nRF52832 one of output (p0.15) lost its power

Turbo J — Fri, 28 Apr 2017 17:53:53 GMT

Did you try using high drive mode NRF_GPIO_PIN_H0H1 on P0.15? Should work better with 100R resistors anyway.

RE: nRF52832 one of output (p0.15) lost its power

AmbystomaLabs — Fri, 28 Apr 2017 14:08:28 GMT

I think you should double check some of your assumptions.

With 100 ohm series resistance and 2.72mA per LED then Vf is about 2.7V. While blue and green LED's generally have a high Vf, red and yellow are normally around 2v. A good sanity check would be to measure the current going into your complete circuit. Should be about 2x2.72mA plus nRF current of maybe 1mA.

Also the manner in which you are driving the LED's is not recommended practice. While the nRF can drive about 5mA per GPIO in high drive mode, you cannot haul 5mA x 20 gpio across the device. There is a limit to how much current you can drag through the core of the nRF.

The recommended practice is the have the gpio active low with the LED current coming from external source that is the same voltage as nRF input. Then the drive current doesn't have to go through the nRF.