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PX4 Hardware designs
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Pixracer R13 #47

Closed LorenzMeier closed 8 years ago

LorenzMeier commented 8 years ago

@pkocmoud @nickarsov @kd0aij This is to discuss schematic revision 13.

PIXRACER-R13.pdf

Pixracer_RC13_CEO_report.pdf

LorenzMeier commented 8 years ago

@nickarsov The issue with the S.BUS inverter (as far as I could see) is that its not bi-directional. So we wouldn't be able to pair or do S.BUS2 telemetry.

nickarsov commented 8 years ago

The changes are on pages 2/5 and 3/5. PB0 hs been separated from PC7. The new labels are: PB0 = FMU_RC_INPUT_TIM and PC7 = FMU_RC_INPUT_SER

  1. PPM: RC_INPUT -> FMU_RC_INPUT_TIM
  2. BIND: PB0 becomes GPIO, HIGH for 100ms, then pulsing 3 active low pulses 50us each, then at least 10ms high, then PB0 must be either configured as input or as 3-stated
  3. Spektrum/SBus are read via U1203 to FMU_RC_INPUT_SER ( PC7 ) and the inversion of the RC_INPUT signal depends on SBUS_INV ( PC13 ). Inversion is with SBUS_INV = 1.
kd0aij commented 8 years ago

@LorenzMeier This is intended to be the optimal electrical config with abandonment of bidirectional SBUS support. I think it should allow proper DSM binding though, using PB0 as I/O

nickarsov commented 8 years ago

Lorenz, can't we use FrSky inverter ( U1202 ) for? We won't be able to use FrSky simultaneously, but just an option?

LorenzMeier commented 8 years ago

@kd0aij It just seems that we will continue to see more single-wire implementations and should position ourselves to be able to do inverted and non-inverted single wire reliably, without strings attached. For RC input we then could connect the TX pin only and use the STM32 in single-wire mode, for FrSky the cable could just pick the TX line and we can do the same in SW.

kd0aij commented 8 years ago

I believe R13 is an interim (1 batch) solution to go into production ASAP. Right Phil? Longer term, the question is whether both S.port and SBUS2 are both compatible with the Maxim 1-wire spec. Are there any 1-wire bidirectional buses (yet) which are non-inverted? Since we're short on GPIOs, it would be nice if the answer is no.

kd0aij commented 8 years ago

I need to look at the STM32 USART single-wire mode. Assuming it turns the IO pin around only when transmitting it should be the ideal solution. Will hopefully be able to do that while debugging the SmartPort code.

LorenzMeier commented 8 years ago

No you won't, because its only using the TX pin. Which will be blocked by the current unidirectional inverter. I guess you understand now what I mean.

kd0aij commented 8 years ago

Oh, I knew that :) But I should be able to breadboard it using a telem port.

nickarsov commented 8 years ago

@Mark: "Are there any 1-wire bidirectional buses (yet) which are non-inverted?" Yes, there is such - DS2480B, which is an old Dallas Semi chip, but it seems it is still in production.

kd0aij commented 8 years ago

Is that something an autopilot would need to support?

On Sun, Jan 17, 2016 at 3:25 PM Nick Arsov notifications@github.com wrote:

@Mark https://github.com/Mark: "Are there any 1-wire bidirectional buses (yet) which are non-inverted?" Yes, there are such - DS2480B, which is an old Dallas Semi chip, but it seems it is still in production.

— Reply to this email directly or view it on GitHub https://github.com/PX4/Hardware/issues/47#issuecomment-172390938.

nickarsov commented 8 years ago

Hi guys, Here is the sch which seems to fulfill all requirements for PPM, Spektrum, Spektrum Sat, SBus I/O, S.Port, SBus2. A truth table integrated. The needed pin can be BOOT1, as after boot, it can be configured as GPIO.

Please check and confirm.

https://drive.google.com/file/d/0BwGTTqZqRwPLTW5QcUZEcWRtUU0/view?usp=sharing

Unfortunately I'm not allowed to upload PDF files here. Also I can't find the Pixracer folder in https://github.com/PX4/Hardware/

nickarsov commented 8 years ago

The truth table was fixed and the link has been updated.

LorenzMeier commented 8 years ago

As of now there is no single wire bus which is not inverted. I can see where you are going with this question. But we don't need a tri-state inverter if it has auto direction sensing.

nickarsov commented 8 years ago

We need a non inverted Spektrum signal.

kd0aij commented 8 years ago

Maxim's 1-wire electrical spec: https://www.maximintegrated.com/en/app-notes/index.mvp/id/214

LorenzMeier commented 8 years ago

Closing, as we have all this now in R14.

limhyon commented 7 years ago

I am now testing with R14, still I had a binding issue of DSMX receiver. Any comments? Also, I couldn't find RC_DSM_BIND parameter when I use Pixracer.

pkocmoud commented 7 years ago

What flight code and version are you testing with?

titeuf007 commented 7 years ago

hey nick where we can download the latest r14 file? i would like to make my own pcb and soldering by myself but i can t arrive to find them sorry for my english i am french