DIY Arduino Transmitter and receiver

 

Hey,

In today's blog we are going to make Transmitter and receiver using Arduino.

REQUIRED STUFF FOR TRANSMITTER:

Arduino pro mini

2 × joystick module

2 × toggle switch

Potentiometer

NRF24L01 Transceiver

HT7333 3.3v voltage regulator

AMS1117 3.3v Voltage regulator

SCHEMATIC FOR TRANSMITTER:

CODE FOR TRANSMITTER:

1. #include <SPI.h>
2. #include <nRF24L01.h>
3. #include <RF24.h>
4. #include <Wire.h>
7. // Define the digital inputs
8. #define jB1 1 // Joystick button 1
9. #define jB2 0 // Joystick button 2
10. #define t1 7 // Toggle switch 1
11. #define t2 4 // Toggle switch 1
12. #define b1 8 // Button 1
13. #define b2 9 // Button 2
14. #define b3 2 // Button 3
15. #define b4 3 // Button 4
17. const int MPU = 0x68; // MPU6050 I2C address
18. float AccX, AccY, AccZ;
19. float GyroX, GyroY, GyroZ;
20. float accAngleX, accAngleY, gyroAngleX, gyroAngleY;
21. float angleX, angleY;
22. float AccErrorX, AccErrorY, GyroErrorX, GyroErrorY;
23. float elapsedTime, currentTime, previousTime;
24. int c = 0;
27. RF24 radio(5, 6); // nRF24L01 (CE, CSN)
28. const byte address[6] = "00001"; // Address
30. // Max size of this struct is 32 bytes - NRF24L01 buffer limit
31. struct Data_Package {
32. byte j1PotX;
33. byte j1PotY;
34. byte j1Button;
35. byte j2PotX;
36. byte j2PotY;
37. byte j2Button;
38. byte pot1;
39. byte pot2;
40. byte tSwitch1;
41. byte tSwitch2;
42. byte button1;
43. byte button2;
44. byte button3;
45. byte button4;
46. };
48. Data_Package data; //Create a variable with the above structure
50. void setup() {
51. Serial.begin(9600);
53. // Initialize interface to the MPU6050
54. initialize_MPU6050();
56. // Call this function if you need to get the IMU error values for your module
57. //calculate_IMU_error();
59. // Define the radio communication
60. radio.begin();
61. radio.openWritingPipe(address);
62. radio.setAutoAck(false);
63. radio.setDataRate(RF24_250KBPS);
64. radio.setPALevel(RF24_PA_LOW);
66. // Activate the Arduino internal pull-up resistors
67. pinMode(jB1, INPUT_PULLUP);
68. pinMode(jB2, INPUT_PULLUP);
69. pinMode(t1, INPUT_PULLUP);
70. pinMode(t2, INPUT_PULLUP);
71. pinMode(b1, INPUT_PULLUP);
72. pinMode(b2, INPUT_PULLUP);
73. pinMode(b3, INPUT_PULLUP);
74. pinMode(b4, INPUT_PULLUP);
76. // Set initial default values
77. data.j1PotX = 127; // Values from 0 to 255. When Joystick is in resting position, the value is in the middle, or 127. We actually map the pot value from 0 to 1023 to 0 to 255 because that's one BYTE value
78. data.j1PotY = 127;
79. data.j2PotX = 127;
80. data.j2PotY = 127;
81. data.j1Button = 1;
82. data.j2Button = 1;
83. data.pot1 = 1;
84. data.pot2 = 1;
85. data.tSwitch1 = 1;
86. data.tSwitch2 = 1;
87. data.button1 = 1;
88. data.button2 = 1;
89. data.button3 = 1;
90. data.button4 = 1;
91. }
92. void loop() {
93. // Read all analog inputs and map them to one Byte value
94. data.j1PotX = map(analogRead(A1), 0, 1023, 0, 255); // Convert the analog read value from 0 to 1023 into a BYTE value from 0 to 255
95. data.j1PotY = map(analogRead(A0), 0, 1023, 0, 255);
96. data.j2PotX = map(analogRead(A2), 0, 1023, 0, 255);
97. data.j2PotY = map(analogRead(A3), 0, 1023, 0, 255);
98. data.pot1 = map(analogRead(A7), 0, 1023, 0, 255);
99. data.pot2 = map(analogRead(A6), 0, 1023, 0, 255);
100. // Read all digital inputs
101. data.j1Button = digitalRead(jB1);
102. data.j2Button = digitalRead(jB2);
103. data.tSwitch2 = digitalRead(t2);
104. data.button1 = digitalRead(b1);
105. data.button2 = digitalRead(b2);
106. data.button3 = digitalRead(b3);
107. data.button4 = digitalRead(b4);
108. // If toggle switch 1 is switched on
109. if (digitalRead(t1) == 0) {
110. read_IMU(); // Use MPU6050 instead of Joystick 1 for controling left, right, forward and backward movements
111. }
112. // Send the whole data from the structure to the receiver
113. radio.write(&data, sizeof(Data_Package));
114. }
116. void initialize_MPU6050() {
117. Wire.begin(); // Initialize comunication
118. Wire.beginTransmission(MPU); // Start communication with MPU6050 // MPU=0x68
119. Wire.write(0x6B); // Talk to the register 6B
120. Wire.write(0x00); // Make reset - place a 0 into the 6B register
121. Wire.endTransmission(true); //end the transmission
122. // Configure Accelerometer
123. Wire.beginTransmission(MPU);
124. Wire.write(0x1C); //Talk to the ACCEL_CONFIG register
125. Wire.write(0x10); //Set the register bits as 00010000 (+/- 8g full scale range)
126. Wire.endTransmission(true);
127. // Configure Gyro
128. Wire.beginTransmission(MPU);
129. Wire.write(0x1B); // Talk to the GYRO_CONFIG register (1B hex)
130. Wire.write(0x10); // Set the register bits as 00010000 (1000dps full scale)
131. Wire.endTransmission(true);
132. }
134. void calculate_IMU_error() {
135. // We can call this funtion in the setup section to calculate the accelerometer and gury data error. From here we will get the error values used in the above equations printed on the Serial Monitor.
136. // Note that we should place the IMU flat in order to get the proper values, so that we then can the correct values
137. // Read accelerometer values 200 times
138. while (c < 200) {
139. Wire.beginTransmission(MPU);
140. Wire.write(0x3B);
141. Wire.endTransmission(false);
142. Wire.requestFrom(MPU, 6, true);
143. AccX = (Wire.read() << 8 | Wire.read()) / 4096.0 ;
144. AccY = (Wire.read() << 8 | Wire.read()) / 4096.0 ;
145. AccZ = (Wire.read() << 8 | Wire.read()) / 4096.0 ;
146. // Sum all readings
147. AccErrorX = AccErrorX + ((atan((AccY) / sqrt(pow((AccX), 2) + pow((AccZ), 2))) * 180 / PI));
148. AccErrorY = AccErrorY + ((atan(-1 * (AccX) / sqrt(pow((AccY), 2) + pow((AccZ), 2))) * 180 / PI));
149. c++;
150. }
151. //Divide the sum by 200 to get the error value
152. AccErrorX = AccErrorX / 200;
153. AccErrorY = AccErrorY / 200;
154. c = 0;
155. // Read gyro values 200 times
156. while (c < 200) {
157. Wire.beginTransmission(MPU);
158. Wire.write(0x43);
159. Wire.endTransmission(false);
160. Wire.requestFrom(MPU, 4, true);
161. GyroX = Wire.read() << 8 | Wire.read();
162. GyroY = Wire.read() << 8 | Wire.read();
163. // Sum all readings
164. GyroErrorX = GyroErrorX + (GyroX / 32.8);
165. GyroErrorY = GyroErrorY + (GyroY / 32.8);
166. c++;
167. }
168. //Divide the sum by 200 to get the error value
169. GyroErrorX = GyroErrorX / 200;
170. GyroErrorY = GyroErrorY / 200;
171. // Print the error values on the Serial Monitor
172. Serial.print("AccErrorX: ");
173. Serial.println(AccErrorX);
174. Serial.print("AccErrorY: ");
175. Serial.println(AccErrorY);
176. Serial.print("GyroErrorX: ");
177. Serial.println(GyroErrorX);
178. Serial.print("GyroErrorY: ");
179. Serial.println(GyroErrorY);
180. }
182. void read_IMU() {
183. // === Read acceleromter data === //
184. Wire.beginTransmission(MPU);
185. Wire.write(0x3B); // Start with register 0x3B (ACCEL_XOUT_H)
186. Wire.endTransmission(false);
187. Wire.requestFrom(MPU, 6, true); // Read 6 registers total, each axis value is stored in 2 registers
188. //For a range of +-8g, we need to divide the raw values by 4096, according to the datasheet
189. AccX = (Wire.read() << 8 | Wire.read()) / 4096.0; // X-axis value
190. AccY = (Wire.read() << 8 | Wire.read()) / 4096.0; // Y-axis value
191. AccZ = (Wire.read() << 8 | Wire.read()) / 4096.0; // Z-axis value
193. // Calculating angle values using
194. accAngleX = (atan(AccY / sqrt(pow(AccX, 2) + pow(AccZ, 2))) * 180 / PI) + 1.15; // AccErrorX ~(-1.15) See the calculate_IMU_error()custom function for more details
195. accAngleY = (atan(-1 * AccX / sqrt(pow(AccY, 2) + pow(AccZ, 2))) * 180 / PI) - 0.52; // AccErrorX ~(0.5)
197. // === Read gyro data === //
198. previousTime = currentTime; // Previous time is stored before the actual time read
199. currentTime = millis(); // Current time actual time read
200. elapsedTime = (currentTime - previousTime) / 1000; // Divide by 1000 to get seconds
201. Wire.beginTransmission(MPU);
202. Wire.write(0x43); // Gyro data first register address 0x43
203. Wire.endTransmission(false);
204. Wire.requestFrom(MPU, 4, true); // Read 4 registers total, each axis value is stored in 2 registers
205. GyroX = (Wire.read() << 8 | Wire.read()) / 32.8; // For a 1000dps range we have to divide first the raw value by 32.8, according to the datasheet
206. GyroY = (Wire.read() << 8 | Wire.read()) / 32.8;
207. GyroX = GyroX + 1.85; //// GyroErrorX ~(-1.85)
208. GyroY = GyroY - 0.15; // GyroErrorY ~(0.15)
209. // Currently the raw values are in degrees per seconds, deg/s, so we need to multiply by sendonds (s) to get the angle in degrees
210. gyroAngleX = GyroX * elapsedTime;
211. gyroAngleY = GyroY * elapsedTime;
213. // Complementary filter - combine acceleromter and gyro angle values
214. angleX = 0.98 * (angleX + gyroAngleX) + 0.02 * accAngleX;
215. angleY = 0.98 * (angleY + gyroAngleY) + 0.02 * accAngleY;
216. // Map the angle values from -90deg to +90 deg into values from 0 to 255, like the values we are getting from the Joystick
217. data.j1PotX = map(angleX, -90, +90, 255, 0);
218. data.j1PotY = map(angleY, -90, +90, 0, 255);
219. }

 SCHEMATIC FOR RECEIVER:

CODE FOR RECEIVER:

1. #include <SPI.h>
2. #include <nRF24L01.h>
3. #include <RF24.h>
4. RF24 radio(10, 9); // nRF24L01 (CE, CSN)
5. const byte address[6] = "00001";
7. unsigned long lastReceiveTime = 0;
8. unsigned long currentTime = 0;
10. // Max size of this struct is 32 bytes - NRF24L01 buffer limit
11. struct Data_Package {
12. byte j1PotX;
13. byte j1PotY;
14. byte j1Button;
15. byte j2PotX;
16. byte j2PotY;
17. byte j2Button;
18. byte pot1;
19. byte pot2;
20. byte tSwitch1;
21. byte tSwitch2;
22. byte button1;
23. byte button2;
24. byte button3;
25. byte button4;
26. };
28. Data_Package data; //Create a variable with the above structure
30. void setup() {
31. Serial.begin(9600);
32. radio.begin();
33. radio.openReadingPipe(0, address);
34. radio.setAutoAck(false);
35. radio.setDataRate(RF24_250KBPS);
36. radio.setPALevel(RF24_PA_LOW);
37. radio.startListening(); // Set the module as receiver
38. resetData();
39. }
40. void loop() {
41. // Check whether there is data to be received
42. if (radio.available()) {
43. radio.read(&data, sizeof(Data_Package)); // Read the whole data and store it into the 'data' structure
44. lastReceiveTime = millis(); // At this moment we have received the data
45. }
46. // Check whether we keep receving data, or we have a connection between the two modules
47. currentTime = millis();
48. if ( currentTime - lastReceiveTime > 1000 ) { // If current time is more then 1 second since we have recived the last data, that means we have lost connection
49. resetData(); // If connection is lost, reset the data. It prevents unwanted behavior, for example if a drone has a throttle up and we lose connection, it can keep flying unless we reset the values
50. }
51. // Print the data in the Serial Monitor
52. Serial.print("j1PotX: ");
53. Serial.print(data.j1PotX);
54. Serial.print("; j1PotY: ");
55. Serial.print(data.j1PotY);
56. Serial.print("; button1: ");
57. Serial.print(data.button1);
58. Serial.print("; j2PotX: ");
59. Serial.println(data.j2PotX);
60. }
62. void resetData() {
63. // Reset the values when there is no radio connection - Set initial default values
64. data.j1PotX = 127;
65. data.j1PotY = 127;
66. data.j2PotX = 127;
67. data.j2PotY = 127;
68. data.j1Button = 1;
69. data.j2Button = 1;
70. data.pot1 = 1;
71. data.pot2 = 1;
72. data.tSwitch1 = 1;
73. data.tSwitch2 = 1;
74. data.button1 = 1;
75. data.button2 = 1;
76. data.button3 = 1;
77. data.button4 = 1;
78. }

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