Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/redoxcode/micropython-ppm_reader
A micropython library to decode PPM signals coming from a RC receiver
https://github.com/redoxcode/micropython-ppm_reader
micropython ppm rc-receiver
Last synced: 3 months ago
JSON representation
A micropython library to decode PPM signals coming from a RC receiver
- Host: GitHub
- URL: https://github.com/redoxcode/micropython-ppm_reader
- Owner: redoxcode
- License: mit
- Created: 2022-12-21T08:48:20.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2023-01-06T08:59:28.000Z (almost 2 years ago)
- Last Synced: 2024-07-28T23:24:49.629Z (3 months ago)
- Topics: micropython, ppm, rc-receiver
- Language: Python
- Homepage:
- Size: 22.5 KB
- Stars: 11
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-micropython - micropython-ppm_reader - Library to decode PPM signals coming from a RC receiver. (Libraries / Communications)
README
[](https://pypi.org/project/micropython-ppm_reader/) [](https://pypi.org/project/micropython-ppm_reader/)
## Description
A micropython library to decode PPM signals coming from a RC receiver (as used for rc planes and drones).
This library is focused on savety and includes functions that can be used to detect a faulty or lost signal.
**For this it is required to init the PpmReader class with the correct number of channels in the PPM signal. This might be a different number than the amount of servo connectors on the RC receiver hardware!**
Created for the use with pi pico, but should work on other boards as well.
You can find the [API documentation](https://github.com/redoxcode/micropython-ppm_reader/#API) and a few [examples](https://github.com/redoxcode/micropython-ppm_reader/#Examples) below.
## Examples
### Print the values of all channels
```Python
from ppm_reader import PpmReader
ppm_pin_id=28
ppm_channels=8
ppmReader=PpmReader(ppm_pin_id,ppm_channels)
while True:
time.sleep(0.5)
print(ppmReader.get_values())
```
### Find the number of channels
```Python
#the number of channels should be known before you init PpmReader
#if the channel number is incorrect only guess_channel_count will work
from ppm_reader import PpmReader
ppm_pin_id=28
ppmReader=PpmReader(ppm_pin_id,channels=0)
while True:
time.sleep(0.5)
print(ppmReader.guess_channel_count())
```
### Find values for min_value and max_value
```Python
#move the controls to the extreme positions and observe the values
from ppm_reader import PpmReader
ppm_pin_id=28
ppm_channels=8
ppmReader=PpmReader(ppm_pin_id,ppm_channels)
while True:
time.sleep(0.5)
print(ppmReader.get_raw_values())
```
### Check for a loss of signal
```Python
from ppm_reader import PpmReader
ppm_pin_id=28
ppm_channels=8
ppmReader=PpmReader(ppm_pin_id,ppm_channels)
#wait initial connection with the remote
while ppmReader.get_valid_packets() == 0:
print("waiting for connection ...")
time.sleep(0.5)
print("connected.")
#got signal, continue to main loop
while True:
last_packet_time=ppmReader.time_since_last_packet()
print(last_packet_time)
if last_packet_time>25000:
#25ms without a new packet
#take security measures here (for example stop all motors)
print("connection lost")
#wait for connection
while ppmReader.time_since_last_packet()>25000:
pass
print("connected again")
else:
#connection ok. Do something here
print(ppmReader.get_values())
```
## API
### class PpmReader(pin_id,channels,min_value=1000,max_value=2000,packet_gap=4000)
- pin_id: GPIO pin connected to the PPM signal comming from the RC receiver.
- channels: Number of channels in the PPM signal. if the channel count is wrong the packts will be considered invalid.
- min_value: Minimum timeframe per channel in us (this should be around 1000us for standard equipment).
- max_value: Minimum timeframe per channel in us (this should be around 2000us for standard equipment).
- packet_gap: Minimum time gap between packets in us (4000us should be used for standard equipment).
```time_since_last_packet()```
- returns the time passed since the last valid packet arrived in us. This will stay below about 5000us if every packet is received correctly. Missing 2 or 3 packets is usually not a problem.
```get_valid_packets()```
- returns the number of valid packets received
```get_inalid_packets()```
- returns the number of invalid packets received
```reset_packet_counters()```
- resets counters for valid and invalid packets received
```get_raw_values()```
- returns a list of all raw timeframes in us in the last valid packet received
```get_raw_value(channel)```
- returns the raw timeframe in us in the last valid packet received for a given channel
- channel: channel to get the value from
```get_values()```
- returns a list of all values in the last valid packet maped to a range of 0.0 to 1.0 (values are not clipped)
```get_value(channel)```
- the value for a given channel in the last valid packet maped to a range of 0.0 to 1.0 (values are not clipped)
- channel: channel to get the value from
```get_values_bi()```
- returns a list of all values in the last valid packet maped to a range of -1.0 to 1.0 (values are not clipped)
```get_value_bi(channel)```
- the value for a given channel in the last valid packet maped to a range of -1.0 to 1.0 (values are not clipped)
- channel: channel to get the value fro
```guess_channel_count()```
- returns the number of channels in the last packet (incase you are not sure how many channels your signal has)