I need to find the NAL header by parsing a RTP packet where each NAL unit is encapsulated into one RTP packet, then i parse the Nal header to know whether it's a PPS unit or not. I tried the following but i got no result:
dataBuffer = (char*)MESSAGE_ReturnPacket(msg);
byte * hdr = (byte*)dataBuffer + RTP_HDR_SIZE; //dataBuffer contains the RTP packet
RTPParsing((byte*)dataBuffer,rp,hdr);
if (rp.nal_type == 8 )
{
printf("\n PPS is found \n");
}
else
{
printf("\n No PPS is found\n");
}
where
int RTPParsing(byte *pData,RTPpacket_t &rp, byte *hdr)
{
if ((pData[0] & 0xc0) != (2 << 6)){
printf("[RTP] version is incorrect! dump = 0x%x 0x%x 0x%x 0x%x
\n",pData[0], pData[1], pData[2], pData[3]);
return 0;
}
/* parse RTP header */
rp.v = (pData[0] & 0xc0) >> 6; /* protocol version */
rp.p = (pData[0] & 0x40) >> 5; /* padding flag */
rp.x = (pData[0] & 0x20) >> 4; /* header extension flag */
rp.cc = (pData[0] & 0x0f); /* CSRC count */
rp.m = (pData[1] & 0x80) >> 7; /* marker bit */
rp.pt = (pData[1] & 0x7F); //Payload Type
rp.seq = ntohs (((unsigned short *) pData)[1]); /* sequence number */
rp.timestamp = ntohl (((unsigned int *) pData)[1]); /* timestamp */
rp.ssrc = ntohl (((unsigned int *) pData)[2]); /* synchronization source */
rp.nal_type = (hdr[1] & 0x1F); // get NAL unit's type
if (rp.cc)
{
for (int i = 0; i < rp.cc; i++)
{
//fprintf (out, " csrc: 0x%08x",ntohl (((unsigned int *) data)[3 + i]));
}
}
return 0;
}
Any help ?
According to RFC6184 in single NAL unit mode, the "The first byte of a NAL unit co-serves as the
RTP payload header"
You offset is incorrect (1 instead of 0):
rp.nal_type = (hdr[1] & 0x1F); // get NAL unit's type
Also, hard-coding RTP_HDR_SIZE as 12 (if that's what you're doing) could cause issues since the size of the header may vary based on extension headers, CSRCs, etc.
Related
I am making HID for some data acquisition system. There are a lot of sensors who store test data and when I need I get to them and connect via USB and take it. USB host sent 3 bytes and USB device, if bytes are correct, sends its stored data. Sounds simple.
Previously it was implemented on PC, but now I try to implement it on STM32F769 Discovery and have some serious problems.
I am using ARM Keil 5.27, code generated with STM32CubeMX 5.3.0. I tried just to make a plain simple program, later to integrate with the entire touchscreen interface. I tried to implement this code in main:
if (HAL_GPIO_ReadPin(BUTTON_GPIO_Port, BUTTON_Pin))
while (HAL_GPIO_ReadPin(BUTTON_GPIO_Port, BUTTON_Pin))
{
Transmission_function();
}
And the function itself:
#define DLE 0x10
#define STX 0x2
uint8_t tx_buf[]={DLE, STX, 120}, RX_FLAG;
uint32_t size_tx=sizeof(tx_buf);
void Transmission_function (void)
{
if (Appli_state == APPLICATION_READY)
{
i=0;
USBH_CDC_Transmit(&hUsbHostHS, tx_buf, size_tx);
HAL_Delay(50);
RX_FLAG=0;
}
}
It should send the message after I press the blue button on the Discovery board. All that I get is Hard Fault. While trying to debug, I tried manually to check after which action I get this error and it was functioning in stm32f7xx_ll_usb.c:
HAL_StatusTypeDef USB_WritePacket(USB_OTG_GlobalTypeDef *USBx, uint8_t *src,
uint8_t ch_ep_num, uint16_t len, uint8_t dma)
{
uint32_t USBx_BASE = (uint32_t)USBx;
uint32_t *pSrc = (uint32_t *)src;
uint32_t count32b, i;
if (dma == 0U)
{
count32b = ((uint32_t)len + 3U) / 4U;
for (i = 0U; i < count32b; i++)
{
USBx_DFIFO((uint32_t)ch_ep_num) = *((__packed uint32_t *)pSrc);
pSrc++;
}
}
return HAL_OK;
}
But trying to scroll back in disassembly I notice, that just before Hard Fault program was in this function inside stm32f7xx_hal_hcd.c, in case GRXSTS_PKTSTS_IN:
static void HCD_RXQLVL_IRQHandler(HCD_HandleTypeDef *hhcd)
{
USB_OTG_GlobalTypeDef *USBx = hhcd->Instance;
uint32_t USBx_BASE = (uint32_t)USBx;
uint32_t pktsts;
uint32_t pktcnt;
uint32_t temp;
uint32_t tmpreg;
uint32_t ch_num;
temp = hhcd->Instance->GRXSTSP;
ch_num = temp & USB_OTG_GRXSTSP_EPNUM;
pktsts = (temp & USB_OTG_GRXSTSP_PKTSTS) >> 17;
pktcnt = (temp & USB_OTG_GRXSTSP_BCNT) >> 4;
switch (pktsts)
{
case GRXSTS_PKTSTS_IN:
/* Read the data into the host buffer. */
if ((pktcnt > 0U) && (hhcd->hc[ch_num].xfer_buff != (void *)0))
{
(void)USB_ReadPacket(hhcd->Instance, hhcd->hc[ch_num].xfer_buff, (uint16_t)pktcnt);
/*manage multiple Xfer */
hhcd->hc[ch_num].xfer_buff += pktcnt;
hhcd->hc[ch_num].xfer_count += pktcnt;
if ((USBx_HC(ch_num)->HCTSIZ & USB_OTG_HCTSIZ_PKTCNT) > 0U)
{
/* re-activate the channel when more packets are expected */
tmpreg = USBx_HC(ch_num)->HCCHAR;
tmpreg &= ~USB_OTG_HCCHAR_CHDIS;
tmpreg |= USB_OTG_HCCHAR_CHENA;
USBx_HC(ch_num)->HCCHAR = tmpreg;
hhcd->hc[ch_num].toggle_in ^= 1U;
}
}
break;
case GRXSTS_PKTSTS_DATA_TOGGLE_ERR:
break;
case GRXSTS_PKTSTS_IN_XFER_COMP:
case GRXSTS_PKTSTS_CH_HALTED:
default:
break;
}
}
Last few lines from Dissasembly shows this:
0x080018B4 E8BD81F0 POP {r4-r8,pc}
0x080018B8 0000 DCW 0x0000
0x080018BA 1FF8 DCW 0x1FF8
Why it fails? How could I fix it? I do not have much experience with USB protocol.
I will post my walkaround this, but I am not sure why it worked. Solution was to use EXTI0 interrupt instead of just detection if PA0 is high, as I showed I used here:
if (HAL_GPIO_ReadPin(BUTTON_GPIO_Port, BUTTON_Pin))
while (HAL_GPIO_ReadPin(BUTTON_GPIO_Port, BUTTON_Pin))
Transmission_function();
I changed it to this:
void EXTI0_IRQHandler(void)
{
/* USER CODE BEGIN EXTI0_IRQn 0 */
if(Appli_state == APPLICATION_READY){
USBH_CDC_Transmit(&hUsbHostHS, Buffer, 3);
}
/* USER CODE END EXTI0_IRQn 0 */
HAL_GPIO_EXTI_IRQHandler(GPIO_PIN_0);
/* USER CODE BEGIN EXTI0_IRQn 1 */
/* USER CODE END EXTI0_IRQn 1 */
}
I'm looking at the following code from STMicroelectronics on implementing USART communication with interrupts
#include <stm32f10x_lib.h> // STM32F10x Library Definitions
#include <stdio.h>
#include "STM32_Init.h" // STM32 Initialization
/*----------------------------------------------------------------------------
Notes:
The length of the receive and transmit buffers must be a power of 2.
Each buffer has a next_in and a next_out index.
If next_in = next_out, the buffer is empty.
(next_in - next_out) % buffer_size = the number of characters in the buffer.
*----------------------------------------------------------------------------*/
#define TBUF_SIZE 256 /*** Must be a power of 2 (2,4,8,16,32,64,128,256,512,...) ***/
#define RBUF_SIZE 256 /*** Must be a power of 2 (2,4,8,16,32,64,128,256,512,...) ***/
/*----------------------------------------------------------------------------
*----------------------------------------------------------------------------*/
#if TBUF_SIZE < 2
#error TBUF_SIZE is too small. It must be larger than 1.
#elif ((TBUF_SIZE & (TBUF_SIZE-1)) != 0)
#error TBUF_SIZE must be a power of 2.
#endif
#if RBUF_SIZE < 2
#error RBUF_SIZE is too small. It must be larger than 1.
#elif ((RBUF_SIZE & (RBUF_SIZE-1)) != 0)
#error RBUF_SIZE must be a power of 2.
#endif
/*----------------------------------------------------------------------------
*----------------------------------------------------------------------------*/
struct buf_st {
unsigned int in; // Next In Index
unsigned int out; // Next Out Index
char buf [RBUF_SIZE]; // Buffer
};
static struct buf_st rbuf = { 0, 0, };
#define SIO_RBUFLEN ((unsigned short)(rbuf.in - rbuf.out))
static struct buf_st tbuf = { 0, 0, };
#define SIO_TBUFLEN ((unsigned short)(tbuf.in - tbuf.out))
static unsigned int tx_restart = 1; // NZ if TX restart is required
/*----------------------------------------------------------------------------
USART1_IRQHandler
Handles USART1 global interrupt request.
*----------------------------------------------------------------------------*/
void USART1_IRQHandler (void) {
volatile unsigned int IIR;
struct buf_st *p;
IIR = USART1->SR;
if (IIR & USART_FLAG_RXNE) { // read interrupt
USART1->SR &= ~USART_FLAG_RXNE; // clear interrupt
p = &rbuf;
if (((p->in - p->out) & ~(RBUF_SIZE-1)) == 0) {
p->buf [p->in & (RBUF_SIZE-1)] = (USART1->DR & 0x1FF);
p->in++;
}
}
if (IIR & USART_FLAG_TXE) {
USART1->SR &= ~USART_FLAG_TXE; // clear interrupt
p = &tbuf;
if (p->in != p->out) {
USART1->DR = (p->buf [p->out & (TBUF_SIZE-1)] & 0x1FF);
p->out++;
tx_restart = 0;
}
else {
tx_restart = 1;
USART1->CR1 &= ~USART_FLAG_TXE; // disable TX interrupt if nothing to send
}
}
}
/*------------------------------------------------------------------------------
buffer_Init
initialize the buffers
*------------------------------------------------------------------------------*/
void buffer_Init (void) {
tbuf.in = 0; // Clear com buffer indexes
tbuf.out = 0;
tx_restart = 1;
rbuf.in = 0;
rbuf.out = 0;
}
/*------------------------------------------------------------------------------
SenChar
transmit a character
*------------------------------------------------------------------------------*/
int SendChar (int c) {
struct buf_st *p = &tbuf;
// If the buffer is full, return an error value
if (SIO_TBUFLEN >= TBUF_SIZE)
return (-1);
p->buf [p->in & (TBUF_SIZE - 1)] = c; // Add data to the transmit buffer.
p->in++;
if (tx_restart) { // If transmit interrupt is disabled, enable it
tx_restart = 0;
USART1->CR1 |= USART_FLAG_TXE; // enable TX interrupt
}
return (0);
}
/*------------------------------------------------------------------------------
GetKey
receive a character
*------------------------------------------------------------------------------*/
int GetKey (void) {
struct buf_st *p = &rbuf;
if (SIO_RBUFLEN == 0)
return (-1);
return (p->buf [(p->out++) & (RBUF_SIZE - 1)]);
}
/*----------------------------------------------------------------------------
MAIN function
*----------------------------------------------------------------------------*/
int main (void) {
buffer_Init(); // init RX / TX buffers
stm32_Init (); // STM32 setup
printf ("Interrupt driven Serial I/O Example\r\n\r\n");
while (1) { // Loop forever
unsigned char c;
printf ("Press a key. ");
c = getchar ();
printf ("\r\n");
printf ("You pressed '%c'.\r\n\r\n", c);
} // end while
} // end main
My questions are the following:
In the handler function, when does the statement ((p->in - p->out) & ~(RBUF_SIZE-1)) ever evaluate to a value other than zero? If RBUF_SIZE is a power of 2 as indicated, then ~(RBUF_SIZE-1) should always be zero. Is it checking if p->in > p->out? Even if this isn't true, the conditional should evaluate to zero anyway, right?
In the line following, the statement p->buf [p->in & (RBUF_SIZE-1)] = (USART1->DR & 0x1FF); is made. Why does the code AND p->in with RBUF_SIZE-1?
What kind of buffer are we using in this code? FIFO?
Not so. For example, assuming 32-bit arithmetic, if RBUF_SIZE == 0x00000100 then RBUF_SIZE-1 == 0x000000FF and ~(RBUF_SIZE-1) == 0xFFFFFF00 (it's a bitwise NOT, not a logical NOT). The check you refer to is therefore effectively the same as (p->in - p->out) < RBUF_SIZE, and it's not clear why it is superior. ARM GCC 7.2.1 produces identical length code for the two (-O1).
p->in & (RBUF_SIZE-1) is the same as p->in % RBUF_SIZE when p->in is unsigned. Again, not sure why the former would be used when the latter is clearer; sure, it effectively forces the compiler to compute the modulo using an AND operation, but given that RBUF_SIZE is known at compile time to be a power of two my guess is that most compilers could figure this out (again, ARM GCC 7.2.1 certainly can, I've just tried it - it produces the same instructions either way).
Looks like it. FIFO implemented as a circular buffer.
Let's say I have a 1024kb data, which is 1kB buffered and transfered 1024 times from a transmitter to a receiver.
The last buffer contains a calculated CRC32 value as the last 4 bytes.
However, the receiver has to calculate the CRC32 buffer by buffer, because of the RAM constraints.
I wonder how to apply a linear distributed addition of CRC32 calculations to match the total CRC32 value.
I looked at CRC calculation and its distributive preference. The calculation and its linearity is not much clear to implement.
So, is there a mathematical expression for addition of calculated CRC32s over buffers to match with the CRC32 result which is calculated over total?
Such as:
int CRC32Total = 0;
int CRC32[1024];
for(int i = 0; i < 1024; i++){
CRC32Total = CRC32Total + CRC32[i];
}
Kind Regards
You did not provide any clues as to what implementation or even what language for which you "looked at CRC calculation". However every implementation I've seen is designed to compute CRCs piecemeal, exactly like you want.
For the crc32() routine provided in zlib, it is used thusly (in C):
crc = crc32(0, NULL, 0); // initialize CRC value
crc = crc32(crc, firstchunk, 1024); // update CRC value with first chunk
crc = crc32(crc, secondchunk, 1024); // update CRC with second chunk
...
crc = crc32(crc, lastchunk, 1024); // complete CRC with the last chunk
Then crc is the CRC of the concatenation of all of the chunks. You do not need a function to combine the CRCs of individual chunks.
If for some other reason you do want a function to combine CRCs, e.g. if you need to split the CRC calculation over multiple CPUs, then zlib provides the crc32_combine() function for that purpose.
When you start the transfer, reset the CrcChecksum to its initial value with the OnFirstBlock method. For every block received, call the OnBlockReceived to update the checksum. Note that the blocks must be processed in the correct order. When the final block has been processed, the final CRC is in the CrcChecksum variable.
// In crc32.c
uint32_t UpdateCrc(uint32_t crc, const void *data, size_t length)
const uint8_t *current = data;
while (length--)
crc = (crc >> 8) ^ Crc32Lookup[(crc & 0xFF) ^ *current++];
}
// In your block processing application
static uint32_t CrcChecksum;
void OnFirstBlock(void) {
CrcChecksum = 0;
}
void OnBlockReceived(const void *data, size_t length) {
CrcChecksum = UpdateCrc(CrcChecksum, data, length);
}
To complement my comment to your question, I have added code here that goes thru the whole process: data generation as a linear array, CRC32 added to the transmitted data, injection of errors, and reception in 'chunks' with computed CRC32 and detection of errors. You're probably only interested in the 'reception' part, but I think having a complete example makes it more clear for your comprehension.
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <time.h>
// ---------------------- buildCRC32table ------------------------------
static const uint32_t CRC32_POLY = 0xEDB88320;
static const uint32_t CRC32_XOR_MASK = 0xFFFFFFFF;
static uint32_t CRC32TABLE[256];
void buildCRC32table (void)
{
uint32_t crc32;
for (uint16_t byte = 0; byte < 256; byte++)
{
crc32 = byte;
// iterate thru all 8 bits
for (int i = 0; i < 8; i++)
{
uint8_t feedback = crc32 & 1;
crc32 = (crc32 >> 1);
if (feedback)
{
crc32 ^= CRC32_POLY;
}
}
CRC32TABLE[byte] = crc32;
}
}
// -------------------------- myCRC32 ----------------------------------
uint32_t myCRC32 (uint32_t previousCRC32, uint8_t *pData, int dataLen)
{
uint32_t newCRC32 = previousCRC32 ^ CRC32_XOR_MASK; // remove last XOR mask (or add first)
// add new data to CRC32
while (dataLen--)
{
uint32_t crc32Top24bits = newCRC32 >> 8;
uint8_t crc32Low8bits = newCRC32 & 0x000000FF;
uint8_t data = *pData++;
newCRC32 = crc32Top24bits ^ CRC32TABLE[crc32Low8bits ^ data];
}
newCRC32 ^= CRC32_XOR_MASK; // put XOR mask back
return newCRC32;
}
// ------------------------------ main ---------------------------------
int main()
{
// build CRC32 table
buildCRC32table();
uint32_t crc32;
// use a union so we can access the same data linearly (TX) or by chunks (RX)
union
{
uint8_t array[1024*1024];
uint8_t chunk[1024][1024];
} data;
// use time to seed randomizer so we have different data every run
srand((unsigned int)time(NULL));
/////////////////////////////////////////////////////////////////////////// Build data to be transmitted
////////////////////////////////////////////////////////////////////////////////////////////////////////
// populate array with random data sparing space for the CRC32 at the end
for (int i = 0; i < (sizeof(data.array) - sizeof(uint32_t)); i++)
{
data.array[i] = (uint8_t) (rand() & 0xFF);
}
// now compute array's CRC32
crc32 = myCRC32(0, data.array, sizeof(data.array) - sizeof(uint32_t));
printf ("array CRC32 = 0x%08X\n", crc32);
// to store the CRC32 into the array, we want to remove the XOR mask so we can compute the CRC32
// of all received data (including the CRC32 itself) and expect the same result all the time,
// regardless of the data, when no errors are present
crc32 ^= CRC32_XOR_MASK;
// load CRC32 at the very end of the array
data.array[sizeof(data.array) - 1] = (uint8_t)((crc32 >> 24) & 0xFF);
data.array[sizeof(data.array) - 2] = (uint8_t)((crc32 >> 16) & 0xFF);
data.array[sizeof(data.array) - 3] = (uint8_t)((crc32 >> 8) & 0xFF);
data.array[sizeof(data.array) - 4] = (uint8_t)((crc32 >> 0) & 0xFF);
/////////////////////////////////////////////// At this point, data is transmitted and errors may happen
////////////////////////////////////////////////////////////////////////////////////////////////////////
// to make things interesting, let's add one bit error with 1/8 probability
if ((rand() % 8) == 0)
{
uint32_t index = rand() % sizeof(data.array);
uint8_t errorBit = 1 << (rand() & 0x7);
// add error
data.array[index] ^= errorBit;
printf("Error injected on byte %u, bit mask = 0x%02X\n", index, errorBit);
}
else
{
printf("No error injected\n");
}
/////////////////////////////////////////////////////// Once received, the data is processed in 'chunks'
////////////////////////////////////////////////////////////////////////////////////////////////////////
// now we access the data and compute its CRC32 one chunk at a time
crc32 = 0; // initialize CRC32
for (int i = 0; i < 1024; i++)
{
crc32 = myCRC32(crc32, data.chunk[i], sizeof data.chunk[i]);
}
printf ("Final CRC32 = 0x%08X\n", crc32);
// because the CRC32 algorithm applies an XOR mask at the end, when we have no errors, the computed
// CRC32 will be the mask itself
if (crc32 == CRC32_XOR_MASK)
{
printf ("No errors detected!\n");
}
else
{
printf ("Errors detected!\n");
}
}
I want to display letter on specific row and column in 16x2 LCD display with 8051 MCU. For Example:
Display "R" at 2nd column in first row
Display "W" at 3rd column in second row
I use these routines for the LCD:
#include<reg51.h>
/* Data pins connected to port P1 of 8051 */
#define Data_Port_Pins (P1)
sbit Register_Select_Pin = P2^0; /* Register Pin of LCD connected to Pin 0 of Port P2 */
sbit Read_Write_Pin = P2^1; /* Read/Write Pin of LCD connected to Pin 1 of Port P2 */
sbit Enable_Pin = P2^2; /* EN pin connected to pin 2 of port P2 */
/* Function for creating delay in milliseconds */
void Delay(unsigned int wait)
{
volatile unsigned i, j;
for(i = 0; i < wait; i++)
for(j = 0; j < 1200; j++);
}
/* Function to send command instruction to LCD */
void LCD_Command (unsigned char command)
{
Data_Port_Pins = command;
Register_Select_Pin =0;
Read_Write_Pin=0;
Enable_Pin =1;
Delay (2);
Enable_Pin =0;
}
/* Function to send display data to LCD */
void LCD_Data (unsigned char Data)
{
Data_Port_Pins = Data;
Register_Select_Pin=1;
Read_Write_Pin=0;
Enable_Pin =1;
Delay(2);
Enable_Pin =0;
}
/* Function to prepare the LCD and get it ready */
void LCD_Initialization()
{
LCD_Command (0x38);
LCD_Command (0x0e);
LCD_Command (0x01);
LCD_Command (0x81);
}
And this is my attempt:
Does it make any sense?
void LCD_Position( char row, char column)
{
unsigned char cmd = 0x80 ; /* Start address */
if( row != 0 ) /*If second row selected ...*/
{
cmd += 0x40 ; /*add start address of second row */
}
cmd += row & 0x0f ;
LCD_Command (cmd);
}
Refer to the data sheet for the LCD device in question. For the common 1602 type module (which the initialisation sequence shown suggests is what you are using) you set the position for the next data write using the Set DDRAM address instruction.
In 2-line display mode the 1st line starts at address 0x00, and the the 2nd line starts at 0x40.
void LCD_Position( int row, int pos)
{
LCD_Command( 0x80 | // Set DDRAM Address
(row == 0) ? 0x00 : 0x40 | // Row selector
(pos & 0x0f) ) ; // Position in row
}
Given (from the data sheet):
The code sets DB7 to 1 (0x80)indicating the Set DDRAM Addresss instruction. The other bits are address bits, but there are more locations in the display RAM than the width of the display, so only 0x00 to 0x0f and 0x40 to 0x4f refer to visible display locations. So if the second row is selected, 0x40 is masked in ((row == 0) ? 0x00 : 0x40), then the character position is masked in ((pos & 0x0f)). Although I have used bit-wise manipulation, the expression could equally be performed arithmetically:
0x80 + (row == 0) ? 0x00 : 0x40 + (pos & 0x0f)
In both cases the & 0x0f ensures the command is not modified and that the character is placed on the display even if the position if out-of-range.
Less succinctly, but perhaps easier to follow:
// Set DDRAM Address command - start of row 0
unsigned char cmd = 0x80 ;
// If second row selected ...
if( row != 0 )
{
// ... add start address of second row
cmd += 0x40 ;
}
// Add row offset. Masked to protect other
// bits from change if row is out of range.
cmd += row & 0x0f ;
// Write command
LCD_Command( cmd ) ;
I'm writing a small embedded program, where I send some commands over uart to the atmega328p chip. The commands start with the character $ and end with the character # (so I know when to perform the parsing). Upon receiving the command I parse it and turn the device on (COMMAND:TURN_ON_I1) or off (COMMAND:TURN_OFF_I1). The application currently looks like this:
// ------- Defines -------- //
#define F_CPU 8000000UL
#include <avr/io.h>
#include <util/delay.h>
#include <avr/power.h>
#include <stdio.h>
#include <string.h>
#include "pinDefines.h"
#include "USART.h"
#define RECEIVE_BUFFER_SIZE 100
// Control output value
#define output_low(port,pin) port &= ~(1<<pin)
#define output_high(port,pin) port |= (1<<pin)
// Set pin mode (input or output)
#define set_input(portdir,pin) portdir &= ~(1<<pin)
#define set_output(portdir,pin) portdir |= (1<<pin)
// The DDRD port contains only two pins:
#define REL_BTN_SIM_2 PD6 // PD6 = REL_BTN_SIM_2
void initUSART(void) { /* requires BAUD */
UBRR0H = UBRRH_VALUE; /* defined in setbaud.h */
UBRR0L = UBRRL_VALUE;
#if USE_2X
UCSR0A |= (1 << U2X0);
#else
UCSR0A &= ~(1 << U2X0);
#endif
/* Enable USART transmitter/receiver */
UCSR0B = (1 << TXEN0) | (1 << RXEN0);
UCSR0C = (1 << UCSZ01) | (1 << UCSZ00); /* 8 data bits, 1 stop bit */
}
void printString(const char myString[]) {
uint8_t i = 0;
while (myString[i]) {
transmitByte(myString[i]);
i++;
}
}
uint8_t receiveByte(void) {
loop_until_bit_is_set(UCSR0A, RXC0); /* Wait for incoming data */
return UDR0; /* return register value */
}
void transmitByte(uint8_t data) {
/* Wait for empty transmit buffer */
loop_until_bit_is_set(UCSR0A, UDRE0);
UDR0 = data; /* send data */
}
int main(void) {
//$COMMAND:TURN_ON_I1#
//$COMMAND:TURN_OFF_I1#
char s[RECEIVE_BUFFER_SIZE];
char readSerialCharacter;
// -------- Inits --------- //
DDRB = 0b00000111;
DDRC = 0b00001000;
DDRD = 0b11000000;
initUSART();
// ------ Event loop ------ //
while (1) {
printString("Waiting for the start of string (char $).\r\n");
do { } while ( receiveByte() != '$'); // Wait for start of string.
// Fill the array until the end of transmission is received
int i=0;
do {
// If nearing end of buffer, don't fill the buffer and exit the loop
if(i<RECEIVE_BUFFER_SIZE-1){
readSerialCharacter = receiveByte();
s[i++] = readSerialCharacter;
}else
break;
} while (readSerialCharacter != '#'); // Wait for end of string.
s[i] ='\0'; // Terminate the string
printString("The whole received command:\r\n");
printString(s);
printString("\r\n");
// Other commands (temperature, relay control)
// REL_BTN_SIM_2
else if(strstr(s, "COMMAND:TURN_ON_I1") != NULL)
{
printString("Will set I1 on!");
output_high(PORTD, REL_BTN_SIM_2);
}
else if(strstr(s, "COMMAND:TURN_OFF_I1") != NULL)
{
printString("Will set I1 off!");
output_low(PORTD, REL_BTN_SIM_2);
}
else
printString("Unknown command.\r\n");
// Clear the buffer
memset(s,'\0', sizeof(s));
}
/* End event loop */
return (0);
}
I noticed that after I send a command around seven or eight times (or more), the serial communication is interrupted or that the command is executed with a delay. I can also see, that the debug strings "Will set I1 off!", "Will set I1 on!" are printed, but the state of the outputs are not changed (or are changed with a delay of a couple of seconds).
I was wondering if someone would know, what I'm doing wrong?
Thanks.
You have a nice definition of set_output(), but you are not using it. So I suspect that you never enabled the output driver. By setting the port register, you just enable the weak pull-up. Maybe that is not strong enough to switch on your relay driver fast. Do you have a capacitor in that driver circuit?