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Dominic Clifton 1925df26ca Add RSSI PWM on CH2 input.

Also support FrSky 1khz RSSI.  See documentation also added in this
commit.

This commit also cleans up the PWM mapping code.  'mask' didn't need to
be a mask and it wasn't possible to add another 'type' since there were
only 4 possible values when it was a mask and they were already defined.  
Combined with switching to using 16 bits instead of 8 for the mapping
configurations, it's now possible to have 256 types instead of 4 at the
expense of a few bytes of flash.

Moved the RSSI calculation into rx_common.c, previously it was in the
main loop.

2014-05-24 00:01:59 +01:00

1.3 KiB

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RSSI

RSSI is a measurement of signal strength. RSSI is very handy so you know when you are going out of range or there is interference.

Some receivers have RSSI outputs. 3 types are supported.

RSSI via PPM channel
RSSI via Parallel PWM channel
RSSI via PWM with PPM RC that does not have RSSI output - aka RSSI PWM

RSSI via PPM

Configure your receiver to output RSSI on a spare channel, then select the channel used via the cli.

e.g. if you used channel 1 then you would set:

set rssi_channel = 1

RSSI via Parallel PWM channel

Connect the RSSI signal to any PWM input channel then set the RSSI channel as you would for RSSI via PPM

RSSI PWM

Connect the RSSI PWM signal to the RC2/CH2 input.

Enable using the RSSI_PWM feature:

feature RSSI_PWM

The feature can not be used when RX_PARALLEL_PWM is enabled.

RSSI PWM Providers

When using RSSI PWM it is possible to use standard ~18ms RSSI signals or a faster 1khz/1m RSSI signal.

The RSSI output on the FrSky X8R (and probably the FrSky X6R) is 1khz.

To support the 1khz rate enable it via the cli:

set rssi_pwm_provider = 1

Value	Meaning
0	~18ms pulse
1	1ms pulse

1.3 KiB Raw Blame History