> For the complete documentation index, see [llms.txt](https://headtracker.gitbook.io/head-tracker/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://headtracker.gitbook.io/head-tracker/getting-started/wiring/ppm-input.md).

# PPM Input

### PPM Input

If you have a PPM signal that is higher than 3.3Volts you will need a voltage divider to reduce the signal. Otherwise you **!Will!** damage your BLE Nano 33.

Hook up as shown in the diagram below. To calculate R1 use the following formula.![](https://raw.githubusercontent.com/wiki/dlktdr/HeadTracker/media/ppm/VoltageDividerEquation.png)

For 5V PPM signal, R1 = (5\*10,000)/3.3 - 10,000 = 5151ohms Round the value **UP** to the nearest commonly available resistor, which is 5600ohm or 5.6k

For 7V PPM Signal, R1 = 7\*10,000/3.3 - 10,000 = 11,212 ohms ==> Rounded Up ==> 12,000ohm or 12 Kohm

It's better to have R value too big, this will result in a lower voltage on the output, which is okay as it will still be detected as a high level.

![](https://3767854731-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Md5nSb70RWQSfl1nJPs%2F-MfWjnFHdZcI6D6NO-HV%2F-MfWjp-DBZCKKGCc0_1k%2Fimage.png?alt=media\&token=dd9cc47b-8372-4d49-bab8-b739ea55004d)