I’m going to use this thread to document my SatNOGS rotator.
I have completed the build, it is now functional, just need to dress things up properly
using
Arduino Uno R3
CNC Shield V3 with A4988 drivers
Connected directly to windows PC, controlled by Gpredict
I’m not using the custom SatNOGS pcb. I’m using a standard Arduino Uno with a CNC shield with A4988’s, which has GREATLY simplified the project as they’re all off the shelf, preassembled, inexpensive components… The Uno, stepper drivers, stepper motors, and shield came to about $60CAD on Amazon Prime, and electronically everything was working within an hour of the parts showing up.
In order to do this I’ve made a few tweaks to the code to take advantage of parts I already have laying around…
I’m using:
Arduino Uno R3 clone
Arduino CNC Shield V3 with 4x A4988’s (only 2 in use) https://www.amazon.ca/gp/product/B016O7TD6O/ref=ppx_yo_dt_b_asin_title_o00__o00_s00?ie=UTF8&psc=1
Nema 17 Stepper Motors
https://www.amazon.ca/gp/product/B06ZXQXD9X/ref=ppx_yo_dt_b_asin_title_o01__o00_s00?ie=UTF8&th=1
Meanwell ELN 60-48D power supply.
Gpredict on Windows 10 PC
Rotctl
Currently I’ve modified easycomms.h to use Serial communications instead of RS485, which lets you connect the arduino to the pc directly without any adapter cables or modifications. I plan on adding the SatNOGS Pi Groundstation at a later time, my primary goal is to track satellites to enable capturing of HRPT.
I also had to modify the rotator_pins.h library to fix a few of the pinouts which changed when I used the CNC shield.
Here’s the pinout thats working for me at the moment.
/*!
* @file rotator_pins.h
*
* It is a header file for pin mapping.
*
* Licensed under the GPLv3
*
*/
#ifndef ROTATOR_PINS_H_
#define ROTATOR_PINS_H_
//#define M1IN1 10 ///< Motor 1 PWM pin
#define M1IN1 2 ///< Motor 1 PWM pin
#define M1IN2 5 ///< Motor 1 PWM pin
#define M1SF 7 ///< Motor 1 digital input, status flag for DC Motor Drivers
#define M1FB A1 ///< Motor 1 analog input, current/load feedback for DC Motor Drivers
#define M2IN1 3 ///< Motor 2 PWM pin
#define M2IN2 6 ///< Motor 2 PWM pin
#define M2SF 7 ///< Motor 2 digital input, status flag for DC Motor Drivers
#define M2FB A0 ///< Motor 2 analog input, current/load feedback for DC Motor Drivers
#define MOTOR_EN 8 ///< Digital output, to enable the motors
#define SW1 11 ///< Digital input, to read the status of end-stop for motor 1
#define SW2 9 ///< Digital input, to read the status of end-stop for motor 2
#define RS485_DIR 2 ///< Digital output, to set the direction of RS485 communication
#define SDA_PIN 3 ///< I2C data pin
#define SCL_PIN 4 ///< I2C clock pin
#define PIN12 12 ///< General purpose I/O pin
#define PIN13 13 ///< General purpose I/O pin
#define A2 A2 ///< General purpose I/O & analog pin
#define A3 A3 ///< General purpose I/O & analog pin
#endif /* ROTATOR_PINS_H_ */I’ve managed to setup the arduino to talk directly to the PC and bypass the Pi completely… I can connect the Arduino directly to my PC and control it via Gpredict.
I did this by editing the easycomm.h file. I basically removed every call to the RS485 library (which allows communications between the Pi and the Arduino directly) and replaced each ‘rs485’ with ‘Serial’ instead…
here’s the edited easycomm.h file so that you can use the arduino sketch directly with gpredict and a PC.
/*!
* @file easycomm.h
*
* It is a driver for easycomm 3 protocol as referred, in Hamlib.
*
* Licensed under the GPLv3
*
*/
#ifndef LIBRARIES_EASYCOMM_H_
#define LIBRARIES_EASYCOMM_H_
#include <Arduino.h>
#include <WString.h>
#include <avr/wdt.h>
//#include "rs485.h"
#include "rotator_pins.h"
#include "globals.h"
#define RS485_TX_TIME 9 ///< Delay "t"ms to write in serial for RS485 implementation
#define BUFFER_SIZE 256 ///< Set the size of serial buffer
#define BAUDRATE 19200 ///< Set the Baudrate of easycomm 3 protocol
//rs485 rs485(RS485_DIR, RS485_TX_TIME);
/**************************************************************************/
/*!
@brief Class that functions for easycomm 3 implementation
*/
/**************************************************************************/
class easycomm {
public:
/**************************************************************************/
/*!
@brief Initialize the RS485 bus
*/
/**************************************************************************/
void easycomm_init() {
// rs485.begin(BAUDRATE);
Serial.begin(9600);
}
/**************************************************************************/
/*!
@brief Get the commands from RS485 and response to the client
*/
/**************************************************************************/
void easycomm_proc() {
char buffer[BUFFER_SIZE];
char incomingByte;
char *Data = buffer;
char *rawData;
static uint16_t BufferCnt = 0;
char data[100];
String str1, str2, str3, str4, str5, str6;
// Read from serial
while (Serial.available() > 0) {
incomingByte = Serial.read();
// Read new data, '\n' means new pacakage
if (incomingByte == '\n' || incomingByte == '\r') {
buffer[BufferCnt] = 0;
if (buffer[0] == 'A' && buffer[1] == 'Z') {
if (buffer[2] == ' ' && buffer[3] == 'E' &&
buffer[4] == 'L') {
// Send current absolute position in deg
str1 = String("AZ");
str2 = String(control_az.input, 1);
str3 = String(" EL");
str4 = String(control_el.input, 1);
str5 = String("\n");
Serial.print(str1 + str2 + str3 + str4 + str5);
} else {
// Get the absolute position in deg for azimuth
rotator.control_mode = position;
rawData = strtok_r(Data, " ", &Data);
strncpy(data, rawData + 2, 10);
if (isNumber(data)) {
control_az.setpoint = atof(data);
}
// Get the absolute position in deg for elevation
rawData = strtok_r(Data, " ", &Data);
if (rawData[0] == 'E' && rawData[1] == 'L') {
strncpy(data, rawData + 2, 10);
if (isNumber(data)) {
control_el.setpoint = atof(data);
}
}
}
} else if (buffer[0] == 'E' && buffer[1] == 'L') {
// Get the absolute position in deg for elevation
rotator.control_mode = position;
rawData = strtok_r(Data, " ", &Data);
if (rawData[0] == 'E' && rawData[1] == 'L') {
strncpy(data, rawData + 2, 10);
if (isNumber(data)) {
control_el.setpoint = atof(data);
}
}
} else if (buffer[0] == 'V' && buffer[1] == 'U') {
// Elevation increase speed in mdeg/s
rotator.control_mode = speed;
strncpy(data, Data + 2, 10);
if (isNumber(data)) {
// Convert to deg/s
control_el.setpoint_speed = atof(data) / 1000;
}
} else if (buffer[0] == 'V' && buffer[1] == 'D') {
// Elevation decrease speed in mdeg/s
rotator.control_mode = speed;
strncpy(data, Data + 2, 10);
if (isNumber(data)) {
// Convert to deg/s
control_el.setpoint_speed = - atof(data) / 1000;
}
} else if (buffer[0] == 'V' && buffer[1] == 'L') {
// Azimuth increase speed in mdeg/s
rotator.control_mode = speed;
strncpy(data, Data + 2, 10);
if (isNumber(data)) {
// Convert to deg/s
control_az.setpoint_speed = atof(data) / 1000;
}
} else if (buffer[0] == 'V' && buffer[1] == 'R') {
// Azimuth decrease speed in mdeg/s
rotator.control_mode = speed;
strncpy(data, Data + 2, 10);
if (isNumber(data)) {
// Convert to deg/s
control_az.setpoint_speed = - atof(data) / 1000;
}
} else if (buffer[0] == 'S' && buffer[1] == 'A' &&
buffer[2] == ' ' && buffer[3] == 'S' &&
buffer[4] == 'E') {
// Stop Moving
rotator.control_mode = position;
str1 = String("AZ");
str2 = String(control_az.input, 1);
str3 = String(" EL");
str4 = String(control_el.input, 1);
str5 = String("\n");
Serial.print(str1 + str2 + str3 + str4 + str5);
control_az.setpoint = control_az.input;
control_el.setpoint = control_el.input;
} else if (buffer[0] == 'R' && buffer[1] == 'E' &&
buffer[2] == 'S' && buffer[3] == 'E' &&
buffer[4] == 'T') {
// Reset the rotator, go to home position
str1 = String("AZ");
str2 = String(control_az.input, 1);
str3 = String(" EL");
str4 = String(control_el.input, 1);
str5 = String("\n");
Serial.print(str1 + str2 + str3 + str4 + str5);
rotator.homing_flag = false;
} else if (buffer[0] == 'P' && buffer[1] == 'A' &&
buffer[2] == 'R' && buffer[3] == 'K' ) {
// Park the rotator
rotator.control_mode = position;
str1 = String("AZ");
str2 = String(control_az.input, 1);
str3 = String(" EL");
str4 = String(control_el.input, 1);
str5 = String("\n");
Serial.print(str1 + str2 + str3 + str4 + str5);
control_az.setpoint = rotator.park_az;
control_el.setpoint = rotator.park_el;
} else if (buffer[0] == 'V' && buffer[1] == 'E') {
// Get the version if rotator controller
str1 = String("VE");
str2 = String("SatNOGS-v2.2");
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'I' && buffer[1] == 'P' &&
buffer[2] == '0') {
// Get the inside temperature
str1 = String("IP0,");
str2 = String(rotator.inside_temperature, DEC);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'I' && buffer[1] == 'P' &&
buffer[2] == '1') {
// Get the status of end-stop, azimuth
str1 = String("IP1,");
str2 = String(rotator.switch_az, DEC);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'I' && buffer[1] == 'P' &&
buffer[2] == '2') {
// Get the status of end-stop, elevation
str1 = String("IP2,");
str2 = String(rotator.switch_el, DEC);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'I' && buffer[1] == 'P' &&
buffer[2] == '3') {
// Get the current position of azimuth in deg
str1 = String("IP3,");
str2 = String(control_az.input, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'I' && buffer[1] == 'P' &&
buffer[2] == '4') {
// Get the current position of elevation in deg
str1 = String("IP4,");
str2 = String(control_el.input, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'I' && buffer[1] == 'P' &&
buffer[2] == '5') {
// Get the load of azimuth, in range of 0-1023
str1 = String("IP5,");
str2 = String(control_az.load, DEC);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'I' && buffer[1] == 'P' &&
buffer[2] == '6') {
// Get the load of elevation, in range of 0-1023
str1 = String("IP6,");
str2 = String(control_el.load, DEC);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'I' && buffer[1] == 'P' &&
buffer[2] == '7') {
// Get the speed of azimuth in deg/s
str1 = String("IP7,");
str2 = String(control_az.speed, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'I' && buffer[1] == 'P' &&
buffer[2] == '8') {
// Get the speed of elevation in deg/s
str1 = String("IP8,");
str2 = String(control_el.speed, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'G' && buffer[1] == 'S') {
// Get the status of rotator
str1 = String("GS");
str2 = String(rotator.rotator_status, DEC);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[0] == 'G' && buffer[1] == 'E') {
// Get the error of rotator
str1 = String("GE");
str2 = String(rotator.rotator_error, DEC);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if(buffer[0] == 'C' && buffer[1] == 'R') {
// Get Configuration of rotator
if (buffer[3] == '1') {
// Get Kp Azimuth gain
str1 = String("1,");
str2 = String(control_az.p, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[3] == '2') {
// Get Ki Azimuth gain
str1 = String("2,");
str2 = String(control_az.i, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[3] == '3') {
// Get Kd Azimuth gain
str1 = String("3,");
str2 = String(control_az.d, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[3] == '4') {
// Get Kp Elevation gain
str1 = String("4,");
str2 = String(control_el.p, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[3] == '5') {
// Get Ki Elevation gain
str1 = String("5,");
str2 = String(control_el.i, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[3] == '6') {
// Get Kd Elevation gain
str1 = String("6,");
str2 = String(control_el.d, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[3] == '7') {
// Get Azimuth park position
str1 = String("7,");
str2 = String(rotator.park_az, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[3] == '8') {
// Get Elevation park position
str1 = String("8,");
str2 = String(rotator.park_el, 2);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
} else if (buffer[3] == '9') {
// Get control mode
str1 = String("9,");
str2 = String(rotator.control_mode);
str3 = String("\n");
Serial.print(str1 + str2 + str3);
}
} else if (buffer[0] == 'C' && buffer[1] == 'W') {
// Set Config
if (buffer[2] == '1') {
// Set Kp Azimuth gain
rawData = strtok_r(Data, ",", &Data);
strncpy(data, rawData + 4, 10);
if (isNumber(data)) {
control_az.p = atof(data);
}
} else if (buffer[2] == '2') {
// Set Ki Azimuth gain
rawData = strtok_r(Data, ",", &Data);
strncpy(data, rawData + 4, 10);
if (isNumber(data)) {
control_az.i = atof(data);
}
} else if (buffer[2] == '3') {
// Set Kd Azimuth gain
rawData = strtok_r(Data, ",", &Data);
strncpy(data, rawData + 4, 10);
if (isNumber(data)) {
control_az.d = atof(data);
}
} else if (buffer[2] == '4') {
// Set Kp Elevation gain
rawData = strtok_r(Data, ",", &Data);
strncpy(data, rawData + 4, 10);
if (isNumber(data)) {
control_el.p = atof(data);
}
} else if (buffer[2] == '5') {
// Set Ki Elevation gain
rawData = strtok_r(Data, ",", &Data);
strncpy(data, rawData + 4, 10);
if (isNumber(data)) {
control_el.i = atof(data);
}
} else if (buffer[2] == '6') {
// Set Kd Elevation gain
rawData = strtok_r(Data, ",", &Data);
strncpy(data, rawData + 4, 10);
if (isNumber(data)) {
control_el.d = atof(data);
}
} else if (buffer[2] == '7') {
// Set the Azimuth park position
rawData = strtok_r(Data, ",", &Data);
strncpy(data, rawData + 4, 10);
if (isNumber(data)) {
rotator.park_az = atof(data);
}
} else if (buffer[2] == '8') {
// Set the Elevation park position
rawData = strtok_r(Data, ",", &Data);
strncpy(data, rawData + 4, 10);
if (isNumber(data)) {
rotator.park_el = atof(data);
}
}
} else if (buffer[0] == 'R' && buffer[1] == 'S'
&& buffer[2] == 'T') {
// Custom command to test the watchdog timer routine
while(1)
;
} else if (buffer[0] == 'R' && buffer[1] == 'B') {
// Custom command to reboot the uC
wdt_enable(WDTO_2S);
while(1);
}
// Reset the buffer an clean the serial buffer
BufferCnt = 0;
Serial.flush();
} else {
// Fill the buffer with incoming data
buffer[BufferCnt] = incomingByte;
BufferCnt++;
}
}
}
private:
bool isNumber(char *input) {
for (uint16_t i = 0; input[i] != '\0'; i++) {
if (isalpha(input[i]))
return false;
}
return true;
}
};
#endif /* LIBRARIES_EASYCOMM_H_ */Custom Arduino mount to hold the Arduino Uno and CNC shield inside the rotator. I hacked together a slim arduino mount, and the stepper motor mount. It’s a tight fit but its perfect
I like what you have done. For a newbie like me it simplifies the motor drive electronics
and lets me do some experimenting from a pc. I have just started ordering parts for my
rotor build and will definitely purchase some Arduino CNC shield board kits.
Hello, I build the rotor version V3, I do not encounter problem for the mechanics, I decided to integrate an Arduino Uno + shield cnc, could you tell me the exact list of the libraries to make the whole thing work.
thank you.
Hello,
Superb your project. I’m very interested.
Do you have a copy of all the libraries required for this project?
I’m also interested in the STL of card support.
Thank you for your answers
Good continuation, good continuation.
Didier
You need to include all the libraries from the satnogs rotator firmware. libraries · master · librespacefoundation / SatNOGS / satnogs-rotator-firmware · GitLab
The modifications I’ve made to those libraries I cut and pasted above (easycomm and rotator_pins)
I’ve uploaded it to Thingiverse
Merci beaucoup pour les bibliothèques et le boitier.
Bonsoir,
J’ai procédé comme vous le conseillez sur cette page.
Remplacé les deux fichiers easycomm et rotator_pins.h dans la librairie, j’ai copié les vôtres à la place.
Dans Arduino IDE, lorsque je lance une vérification, une erreur se produit sur la ligne
<AccelStepper.h> ???
AccelStepper.h: No such file or directory ???
Désolé je suis vraiment débutant et j’apprends progressivement.
Merci pour vos réponses.
Bonne soirée.
I think they forgot to include that library. I just made a merge request to have that file added, I must have just downloaded it when trying to get it to run (I can’t remember)
https://www.airspayce.com/mikem/arduino/AccelStepper/files.html
if any script ever pops up asking for a library you can always usually find them via google, download and add them to library folder
Other things I had to do to make my modified rotator work properly:
reverse the direction of the elevation axis. This was accomplished by swapping two of the wires going to the servo motor (swap the wires going to one of the coils)
At first, it was only moving half as far as each command (if i asked for 180 rotation, it would do 90, if i asked for 80 elevation, it would do 40). Changing the Gear Ratio to 108 from the default 54 fixed this… I’m not sure if this was the proper way to do it, but it seems to work well. I have a feeling my microstepping jumpers might not be set the same as in the sketch (I have all my jumpers in to enable the highest microstepping). You could change the microsteps in the sketch, but there seems to be a lot of other variables which rely on it and might need to be modified to make that change? It seemed easier to just double the gear ratio, and it behaves as expected now? I might tweak that.
#define RATIO 108 ///< Gear ratio of rotator gear box default 54
Azimuth Stepper Driver/motor connected to Y port on CNC Board
Elevation Stepper Driver/motor connected to X port on CNC Board
The End stop switch for elevation is connected to the X end stop on the CNC board (+ or -)
The End stop switch for azimuth is connected to the Z end stop on the CNC board (+ or -)
I also had to change the default home state from HIGH to LOW
#define DEFAULT_HOME_STATE LOW ///< Change to LOW according to Home sensor
Hey!!
It would be nice to make a wiki page like this, in order to document all the process about the CNC shield for arduino board.
Also you can add your changes in firmware,
.According to readme intructions, you must install the AccelStepper library.
Thank you very much for your explanations, did you put jumpers to the drivers, if so how many micro steppes?
Rémy.
I didn’t have the proper jumpers because they didn’t come with the board!(tsk, tsk)… so I just put a blob of solder to connect all 6 pins on the back of the board (to enable the highest level of microstepping)
3D printing a case out of PETG right now! it’s going to be a long print… easier than building a case by hand though.
I’ll upload the STL once I know it works. I plan on cutting the hole for the bottom axis by hand… I was more worried about getting the dimensions right, I didn’t want to make the hole in the wrong spot.
The bottom will be 195mm tall, and the top cap will be similar dimensions, probably a bit shorter, (except with cutouts for the elevation axis) and will overlap the lower box to make things waterproof.
This is what I’m thinking for the top… the bottom seems to be coming along well
It’s getting there! Going to bed now will wake up to completed box or a disaster in the morning haha
Hello, a little news of the progress of the rotator, I finished the mechanical parts for two rotators, one for me and one for friend he does not have the printer 3 d, I wait for the profiles of at motedis with impatience to finish the project, see you soon.
Rémy.
