Passing string to uint8_t array in arduino - arrays

Question

I have to send an integer counter as 'num' through XBee (in API mode) from Arduino. For this purpose I have to convert this integer to String and then to uint8_t array as it is needed in API frame to transmit.
Apart from other details I've converted my integer to string like
String str;
int num = 0;
char cstr[16];
void loop() {
num++;
str = String(num);
str.toCharArray(cstr,16);
Serial.println(cstr); // this shows the correct result, means int is converted to String correctly
uint8_t data[] = {cstr}; // passing String to uint8_t array
XBeeAddress64 addr64 = XBeeAddress64();
addr64.setMsb(0x00000000);
addr64.setLsb(0x00000000);
ZBTxRequest zbTx = ZBTxRequest(addr64, data, sizeof(data));
xbee.send(zbTx);
int count = sizeof(data);
for (int i = 0; i < count; i++) {
if (i == (count-1)) {
Serial.print(data[i]); // here it prints "104" of ASCII which is equal to "h"
}
}
}
It also transmit it as like that Serial print i.e. ('104').
Please point out if I am making any mistake and guide me if I didn't do it as required.

Answer 1

First get rid of those cstr and String:
int num = 0;
//char cstr[16];
char data[16] = {'\0'}; // Initialize data array
void setup() {
}
void loop() {
num++;
//str = String(num);
//str.toCharArray(cstr,16);
itoa (num, data, 10);
Serial.println(data);
// To get the number of elements in the array use
uint8_t datalen = strlen(data);
// Black box see lib for details
XBeeAddress64 addr64 = XBeeAddress64();
addr64.setMsb(0x00000000);
addr64.setLsb(0x00000000);
ZBTxRequest zbTx = ZBTxRequest(addr64, data, datalen);
xbee.send(zbTx);
// Print test
Serial.println("Content of data: ");
Serial.print(data);
Serial.print(" datalen: ");
Serial.print(datalen);
}
This should work as you expect. To copy an array you would use strcpy (or memcopy with malloc and free), to get the number of elements use strlen.
EDIT:
Here is a tested code (just copy andpaste and first replace only the include to your xbee lib:
#include "Xbee.h" //-> Change to your xbee lib
uint16_t num = 0;
char xdata[16] = {'\0'};// Initialize data array
char numbuf[16] = {'\0'}; // initialize number buffer
long currentMillis = 0;
void setup() {
Serial.begin(115200);
currentMillis = millis();
}
void loop() {
if (millis() - currentMillis > 1000) { // 1 sec timer to prevent overflow due to hammering xbee with data -> tune to your stable transmission
num++;
itoa (num, numbuf, 10); // Num buffer
strcpy(xdata, numbuf); // Copy content of num buffer to data array
Serial.println(xdata);
// To get the number of elements in the array use
uint16_t datalen = strlen(xdata);
// Black box see lib for details
XBeeAddress64 addr64 = XBeeAddress64();
addr64.setMsb(0x00000000);
addr64.setLsb(0x00000000);
ZBTxRequest zbTx = ZBTxRequest(addr64, data, datalen);
xbee.send(zbTx);
// Print test
Serial.print("Content of xdata: ");
Serial.print(xdata);
Serial.print(" datalen: ");
Serial.println(datalen);
currentMillis = millis(); // reset timer
}
}
The result in serial monitor is:
1
Content of xdata: 1 datalen: 1
2
Content of xdata: 2 datalen: 1
3
Content of xdata: 3 datalen: 1
4
Content of xdata: 4 datalen: 1
....
864
Content of xdata: 864 datalen: 3
865
Content of xdata: 865 datalen: 3
866
Content of xdata: 866 datalen: 3
So all works as expected, no 104 or similar. Please first copy paste - test it - and then your additions