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appendix rtl sdr gpio

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Rodrigo Freire edited this page Nov 20, 2019 · 10 revisions

Appendix 2 - Using RTL-SDR GPIO

In order to be able to use the RTL-SDR's GPIO ports, you will need the rtl_biast tool from this special RTL-SDR Blog build.

While in RTL-SDR you have the markings 29, 30, 31 and 32, these does not correspond to the actual GPIO number.

RTL-SDR GPIO Pins

RTL-SDR GPIO header

Use the following table to translate the board numbers to the actual GPIO number:

+---------+-----------+
| SDR PIN |  GPIO NR  |
+---------+-----------+
|   29    |     5     |
|   30    |     4     |
|   31    |     2     |
|   32    |     1     |
+---------+-----------+

RTL-SDR board GPIO and Software GPIO mapping

After installing the required (if your Windows doesn't have it) Windows C++ runtimes, use the rtl_biast.exe file to flip the GPIO signal of interest.

For example, flipping the GPIO Pin 30 to ON:

> rtl_biast -d 0 -b 1 -g 4

The above command translates to:

  • -d 0 - RTL-SDR Board #0 (use the proper number if you have more than one dongles)
  • -b 1 - Enable signal. Conversely, to turn the signal off use -b 0
  • -g 4 - GPIO #4, translated from GPIO 30 from aforementioned table

Currently, there are no software provisions to find out the current bias state of each GPIO port. There's a pull request for showing the Bias Tee current state - But nothing involving the individual GPIO ports.

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