No feedback on RS-485 communication?


Looking at the schematic, again, the RS-485 to TTL converter chip (U2) is only half duplex and the transmit side is hardwired off? By doing this you get no feedback to Gpredict as to where the rotor actually is.

What was the thinking on doing that? Why not use full duplex like a regular rotor (i.e. meters showing you where you are)?

Hey, half duplex means that RX and TX use the same bus (pair of wires A,B), that is the reason of pins RE/DE that controlled by RTS in PCB. The default state is receive mode, RTS is LOW. When the controller receives a packet that need feedback, the state of the controller changes to transmit, RTS is HIGH.

OK, after looking at the schematic I do see where the device enable lines are being controlled (I’ve been using Eagle for 20 years, and switched to kicad about a year ago…still learning the differences…

Looking at the rotor_pins.h file, I see the RS-485 direction, with a 2 next to it. Does that mean IO pin 2? If so then that doesn’t match the schematic…


Pin 2 is IO pin. Why that doesn’t match with the schematic?

  • But from the rotator_pins.h I have:

  • /*

    • rotator_features.h
    • Created on: Nov 12, 2017
    •  Author: azisi
  • */

  • #ifndef ROTATOR_PINS_H_

  • #define ROTATOR_PINS_H_

  • #define M1IN1 6

  • #define M1IN2 5

  • #define M1SF 7

  • #define M1FB A1

  • #define M2IN1 11

  • #define M2IN2 3

  • #define M2SF 10

  • #define M2FB A0

  • #define MOTOR_EN 8

  • #define SW1 9

  • #define SW2 4

  • #define RS485_DIR 2

  • #define SDA_PIN 3

  • #define SCL_PIN 4

  • #define PIN12 12

  • #define PIN13 13

  • #define A2 A2

  • #define A3 A3

  • #endif /* ROTATOR_PINS_H_ */

  • So, if I am reading this right, the M1IN1 is Pin 6, M1IN2 is pin 5, but the schematic has pin 6 as M2IN2 and pin 5 is RTS but the header file has it as M1IN2.

  • And these pins do NOT match up with the schematic (as well as more of the pins). So either the software doesn’t match the schematic or vice versa.

  • What am I missing here???

From firmware here everything match up with the schematic.
PD3/3 in pin with number 6 and has net name M2IN2.

Does it match up with the header code listed above? Because teh header file I have doesn’t even match your posted schematic section…Again, what am I missing???

What version of the PCB and the software are you referring to? Can you supply direct links on both the PCB layout and the controller software please? Something is not syncing up on this thread and I cannot get the controller to work on RS-485 as well and any motor functions…

For example - Even the I2C pins don’t match with the header file that is on the repository:
From your schematic above: SDA is pin 23, and SCL is Pin 24
But the header file has: #define SDA pin as 3, and SCL pin as 4

I can go through the entire list but they (schematic and header file) DO NO match. What header file are YOU comparing to? A direct link please.

Finally! Yes, the source code HAS changed.



Can someone PLEASE show me where the schematic AND the source files are EXACTLY the same? this is really pathetic to be struggling like this to get supposedly proven software up and runnin

Hello, @herbsims

The rotator (mechanical and electronics) subproject of SatNOGS is a volunteer-run project with long active development and testing. As you can see on repositories most of the things you are trying out are in “master” branches and in active development (vs being on tagged tested releases). You are not providing which release, which tag, which version you are using so we can be more helpful in trying to figure out your issue.

Yelling and cursing are really not helpful, and consider this a warning on a public forum. I understand your frustration but we are all here in goodwill helping each other like a community does. Please try to be respectful of that.

Thanks a lot in adavnce


I understand completely and my apologies. Yes, my frustration got the better of me last night. In the future I will make sure that I post as much information concerning the modules that I am trying to figure out.