[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Paparazzi-devel] Futaba SBUS through R/C connector on Umarim

From: Gautier Hattenberger
Subject: Re: [Paparazzi-devel] Futaba SBUS through R/C connector on Umarim
Date: Mon, 15 Jun 2015 23:05:14 +0200
User-agent: Mozilla/5.0 (X11; Linux i686; rv:31.0) Gecko/20100101 Thunderbird/31.7.0


Le 14/06/2015 15:00, Joseph Muhlhausen a écrit :
Hi Gautier Thanks this is very useful. I had not thought about the interrupts.

I did a little bit more research:
- There is a SBUS to CPPM from Frsky which I tested. It works well but it becomes an anagogic signal and the SBUS SIGNAL_LOST bit is not carried through.
It all depends on the behavior of the converter when the signal is lost. If it keep sending a "failsafe" value, you'll not be able to tell if it is lost, but if the signal becomes null, you'll have the info.

A hack we did some time ago for lpc21 is to use the led signal of the receiver (if the color is changed/tuned off when the signal is lost) and put this to a GPIO input. Then you need to define some stuff to turn this into RC_LOST signal.

See sw/airborne/arch/lpc21/subsystems/radio_control/ppm_arch.h:54
And for the airframe (for pin P0.17):

    <subsystem name="radio_control" type="ppm">
      <define name="USE_PPM_RSSI_GPIO"/>
      <define name="PPM_RSSI_IOPIN" value="IO0PIN"/>
      <define name="PPM_RSSI_PIN" value="17"/>
      <define name="PPM_RSSI_VALID_LEVEL" value="0"/>

- I can use a Lisa M2 (easier to find) with an inverter.
I guess it should work, but I don't use Lisa boards

- I could write a SBUS serial driver for I2C? (I am not sure about this one).
I don't think it works

How difficult would it be to write and SPI driver for xbee?
I never tried, probably a bit annoying....



On Sun, Jun 14, 2015 at 4:23 AM, Gautier Hattenberger <address@hidden> wrote:

If plan to use an UART input for SBUS, you'll also need to invert the signal (the SBUS signal is not a standard serial: different idle level, unusual baud rate), and as you figured it, there is only two UART on Umarim board. An no easy solution:
- fix the gps-i2c driver if you are using an ublox gps.
- implement gpio based (probably better use the input capture pin (PPM)) to read the signal by hand (benefit is that you don't need the inverter, but it will generate a lot of interrupts).
- write an spi driver for XBee.
- use an Apogee board (unfortunately a bit difficult to find these days... ).


Le 13/06/2015 23:58, Joseph Muhlhausen a écrit :
According to the data sheet for NXP LPC2148 there are only two UART available. I wonder if there is a way to connect it via SPI or IC2.

On Thu, Jun 11, 2015 at 2:09 PM, Joseph Muhlhausen <address@hidden> wrote:
I am switching to a futaba sbus system and it looks like both UART port are occupied by an xbee and a GPS on Umarim lite 2.0. 

Can I read the sbus signal via the PPM pin on Umarim?
Or can I use a GPIO pin instead?


Paparazzi-devel mailing list

Paparazzi-devel mailing list

Paparazzi-devel mailing list

reply via email to

[Prev in Thread] Current Thread [Next in Thread]