uart between atmega328p (C) and Feather m0 (Arduino) receive - c

Question

I want to send data from my ac/gy via atmega328p to a feather m0 module. The atmega is programmed in C using the following github code: https://github.com/YifanJiangPolyU/MPU6050
And the Arduino code for receiving data within the LoRa module is shown below:
void do_send(osjob_t* j){
// Check if there is not a current TX/RX job running
if (LMIC.opmode & OP_TXRXPEND) {
Serial.println(F("OP_TXRXPEND, not sending"));
} else {
// Prepare upstream data transmission at the next possible time.
byte strArray[30];
int i = 0;
if(Serial1.available()>0) {
while (Serial1.available()>0){
strArray[i] = Serial1.read();
i++;
}
// send the 6 bytes payload to LoRaWAN port 7 --> now port 1
LMIC_setTxData2(1, strArray, sizeof(strArray), 1);
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on by making the voltage HIGH //optional: for confirmation
}
}
}
// Next TX is scheduled after TX_COMPLETE event.
//delay(60000);
void loop() {
os_runloop_once();
}
However, I can't seem to receive anything and can't send a "char array" to the gateway using the LMIC function apparently, so trying to receiving data within a byte array instead. Any help or tips regarding this is greatly appreciated. I'll also include the main.c code for the atmega328P down here below:
#define F_CPU 16000000UL
#define BAUD 9600
#include <inttypes.h>
#include <avr/sfr_defs.h>
#include <stdint.h>
#include <avr/io.h>
#include <util/delay.h>
#include <util/setbaud.h>
#include <avr/interrupt.h>
#include <math.h>
#include "mpu6050.h"
#include "mpu6050_reg.h"
#include "i2c.h"
#include "uart.h"
void timer_setup();
void get_time(double* dt);
volatile double count;
const double unit_t = 8/16000000;
int main(void){
sei();
uart_init();
i2c_init();
DDRB |= _BV(5);
uint8_t ret;
int16_t accel_buff[3], gyro_buff[3];
double accelX, accelY, accelZ;
double gyroX, gyroY, gyroZ;
double biasX, biasY;
double phi_accel, theta_accel;
double phi_innov, theta_innov;
double phi_est, theta_est;
double phi_prev, theta_prev;
double dt;
char s[30];
// initialize & test MPU5060 availability
ret = i2c_start(MPU6050_ADDRESS+I2C_WRITE);
if(~ret){
PORTB |= _BV(5);
_delay_ms(200);
PORTB &= ~(_BV(5));
}
mpu6050_init();
timer_setup();
// find gyro bias
biasX = 0;
biasY = 0;
uint8_t i;
for(i=0; i<20; i++){
mpu6050_read_gyro_ALL(gyro_buff);
biasX += gyro_buff[0];
biasY += gyro_buff[1];
}
biasX = biasX/20*(3.14159/180)/1000/32768;
biasY = biasY/20*(3.14159/180)/1000/32768;
// initialization for Kalman filter
double P = 0.0;
double Q = 0.001;
double R = 0.03;
double Pp, K;
mpu6050_read_accel_ALL(accel_buff);
phi_prev = atan2(accelY, accelZ); // row
theta_prev = atan2(-accelX, sqrt(accelY*accelY+accelZ*accelZ)); // pitch
for(;;){
get_time(&dt);
mpu6050_read_accel_ALL(accel_buff);
mpu6050_read_gyro_ALL(gyro_buff);
// acceleration (m/s^2)
accelX = accel_buff[0]*9.8*2/32768;
accelY = accel_buff[1]*9.8*2/32768;
accelZ = accel_buff[2]*9.8*2/32768;
// gyro rate (rad/s)
gyroX = gyro_buff[0]*(3.14159/180)/1000/32768;
gyroY = gyro_buff[1]*(3.14159/180)/1000/32768;
gyroZ = gyro_buff[2]*(3.14159/180)/1000/32768;
// estimation
phi_est = phi_prev + dt*(gyroX - biasX);
theta_est = theta_prev + dt*(gyroY - biasY);
Pp = P+Q;
// innovation
phi_accel = atan2(accelY, accelZ); // row
phi_innov = phi_accel - phi_est;
theta_accel = atan2(-accelX, sqrt(accelY*accelY+accelZ*accelZ)); // pitch
theta_innov = theta_accel - theta_est;
// Kalman gain
K = Pp/(Pp+R);
// correction
phi_prev = phi_prev + K*phi_innov;
theta_prev = theta_prev + K*theta_innov;
P = (1-K)*Pp;
uart_putchar('\n');
_delay_ms(10);
uart_putdouble(phi_prev); //phi, row
uart_putdouble(theta_prev); //theta, pitch
uart_putdouble(dt);
//_delay_ms(10);
}
}//end of main
void timer_setup(){
TCCR1A = 0x00;
TIMSK1 |= _BV(TOIE1);
TCCR1B |= _BV(CS11);
TCCR1B &= ~( _BV(CS12) | _BV(CS10)); // prescaler=8
}
void get_time(double * dt){
cli();
uint8_t l = TCNT1L;
uint8_t h = TCNT1H;
uint16_t step = h<<8 | l;
*dt = (double)step*5e-7 + count*0.032768;
count = 0;
sei();
}
// timer 1 overflow interrupt handler
SIGNAL(TIMER1_OVF_vect){
count += 1;
}

Answer 1

Connect the board to the PC and check in the Arduino IDE Serial Monitor if you can get or send data.
If your serial communication doesn't work, you can check if you are past a point in execution by turning on the led on the board. Most development boards have at least 1, and with Arduino is just a matter of setting the pin as output and digitalWrite(LED_BUILTIN, 0) in setup, then digitalWrite(LED_BUILTIN, 1) at the point you want to check.
If your atmega328p is on an arduino board (e.g. uno, nano etc) you should check in the same way for it, too. Both the serial and past-the-point verification.
I'd to that, then rely on the serial for debugging for a while.
I'm curious, do you think the condition "if(Serial1.available()>0)" is true?