I want to communicate RPI3 with atmega8 via uart. In atmega I set 9600 baud rate, 8bits, no parity bit and one stop bit. I my rpi I'm using WiringPi library and this is my code:
int fd;
if ((fd = serialOpen ("/dev/ttyAMA0", 9600)) < 0)
{
cout << "Error";
return 1 ;
}
if (wiringPiSetup () == -1)
{
cout << "Error";
return 1 ;
}
serialPutchar (fd, 50) ;
But .. I atmega I don't receive this '50'. Maybe should I configure connection in termios ? Any Idea ?
When I try to use the code I receive a "2" in the ASCII table dec 50.
If you receive wrong data you might convert it first. If you don't receive data there might be a problem with the tty configuration or the hardware setup.
Related
I'm running into some initial LIDAR connection issue with simultaneously connecting 4 Slamtec RPLIDAR A3 using MATALB
with the provided interface library found here: https://github.com/ENSTABretagneRobotics/Hardware-MATLAB
The issue is that I am having to retry the connection on at least one of the LIDARS before it connects.
And it can also vary with LIDAR that is. That is, all but one LIDAR connects the first time.
One time, it could be LIDAR on one COM port, another time it could be a LIDAR on another COM port.
This is the way it is set up right now.
Basically MATALB loads the provided interface library, hardwarex.dll. That exposes some library methods to be used by MATLAB.
The method to connect the LIDAR does the following:
Opens the RS232 port
Sets port options
Gets some info and health statuses form lidar
Sets the motor PWM to zero (stop lidar motor)
Uses express scan mode option
Here somewhere the communication will error out.
Using a serial sniffer I was able to see that the LIDAR errors out after the following message to the LIDAR:
a5 f0 02 ff 03 ab a5 25 a5 82 05 00 00 00 00 00 22
Which I tracked to the following library methods, in that order
SetMotorPWMRequestRPLIDAR()
CheckMotorControlSupportRequestRPLIDAR()
StopRequestRPLIDAR()
StartExpressScanRequestRPLIDAR() <-- Error here
To which the LIDAR responds with:
a5 5a 54 00 00 40 82
Where as a successfully connection response from the LIDAR much longer in content.
Things I've tried
Drain (force all write data) the write buffer with the interface libraries DrainComputerRS232Port() method before and/or after any write to lidar.
Setting the TX/Write OS FIFO buffer to FILE_FLAG_NO_BUFFERING (ie. WriteFile()).
Changing the Hardware FIFO buffer form max (16) to min (1).
Using MATLAB's serial() command to flush any input or output buffers prior to loading the library or trying the connections.
This is the system and settings I am working with
Lidar (x4):
Slamtec RPLIDAR A3
Firmware 1.26
Connected via USB (no USB hub used)
No other COM port devices connected
Computer
OS: Windows 10 Pro - Build 1903
CPU: Intel Xeon 3.00Ghz
RAM: 64 GB
HD: SSD - 512GB NVMe
Serial Port Settings
Boud Rate: 256000
Timeout: 1000
Software
MATLAB R2018b (9.5.0)
I've been banging my head on the wall with this. Any help is much much appreciated!
I'm going to answer my own question. And anyone is interested in a more detailed discussion please refer to the issue posted on the MATLAB RPLIDAR repo:
https://github.com/ENSTABretagneRobotics/Hardware-MATLAB/issues/2
As I mentioned, when debugging, the error seemed to happen ConnectRPLIDAR() --> StartExpressScanRequestRPLIDAR(), then specifically here:
// Receive the first data response (2 data responses needed for angles computation...).
memset(pRPLIDAR->esdata_prev, 0, sizeof(pRPLIDAR->esdata_prev));
if (ReadAllRS232Port(&pRPLIDAR->RS232Port, pRPLIDAR->esdata_prev, sizeof(pRPLIDAR->esdata_prev)) != EXIT_SUCCESS)
{
// Failure
printf("A RPLIDAR is not responding correctly. \n");
return EXIT_FAILURE;
}
What seemed to have happened before that is after the command being send out in WriteAllRS232Port(), sometimes it would not read a response in the ReadAllRS232Port(), esdata_prev would be nothing.
We tried implementing a mSleep(500) delay before that second ReadAllRS232Port(), and it seemed to help (my guess that the lidar was slow to respond), but the issue did not get resolved fully.
The following is what made it work every time with 4 lidars:
inline int StartExpressScanRequestRPLIDAR(RPLIDAR* pRPLIDAR)
{
unsigned char reqbuf[] = { START_FLAG1_RPLIDAR,EXPRESS_SCAN_REQUEST_RPLIDAR,0x05,0,0,0,0,0,0x22 };
unsigned char descbuf[7];
unsigned char sync = 0;
unsigned char ChkSum = 0;
// Send request to output/tx OS FIFO buffer for port
if (WriteAllRS232Port(&pRPLIDAR->RS232Port, reqbuf, sizeof(reqbuf)) != EXIT_SUCCESS)
{
printf("Error writing data to a RPLIDAR. \n");
return EXIT_FAILURE;
}
// Receive the response descriptor.
memset(descbuf, 0, sizeof(descbuf)); // Alocate memory
if (ReadAllRS232Port(&pRPLIDAR->RS232Port, descbuf, sizeof(descbuf)) != EXIT_SUCCESS)
{
printf("A RPLIDAR is not responding correctly. \n");
return EXIT_FAILURE;
}
// Quick check of the response descriptor.
if ((descbuf[2] != 0x54) || (descbuf[5] != 0x40) || (descbuf[6] != MEASUREMENT_CAPSULED_RESPONSE_RPLIDAR))
{
printf("A RPLIDAR is not responding correctly. \n");
return EXIT_FAILURE;
}
// Keep anticipating a port read buffer for 1 second
int timeout = 1500;
// Check it every 5 ms
// Note on Checking Period Value:
// Waiting on 82 bytes in lidar payload
// 10 bits per byte for the serial communication
// 820 bits / 256000 baud = 0.0032s = 3.2ms
int checkingperiod = 5;
RS232PORT* pRS232Port = &pRPLIDAR->RS232Port;
int i;
int count = 0;
// Wait for something to show up on the input buffer on port
if (!WaitForRS232Port(&pRPLIDAR->RS232Port, timeout, checkingperiod))
{
//Success - Something is there
// If anything is on the input buffer, wait until there is enough
count = 0;
for (i = 0; i < 50; i++)
{
// Check the input FIFO buffer on the port
GetFIFOComputerRS232Port(pRS232Port->hDev, &count);
// Check if there is enough to get a full payload read
if (count >= sizeof(pRPLIDAR->esdata_prev))
{
// Thre is enough, stop waiting
break;
}
else
{
// Not enough, wait a little
mSleep(checkingperiod);
}
}
}
else
{
//Failure - After waiting for an input buffer, it wasn't there
printf("[StartExpressScanRequestRPLIDAR] : Failed to detect response on the input FIFO buffer. \n");
return EXIT_FAILURE;
}
// Receive the first data response (2 data responses needed for angles computation...).
memset(pRPLIDAR->esdata_prev, 0, sizeof(pRPLIDAR->esdata_prev));
if (ReadAllRS232Port(&pRPLIDAR->RS232Port, pRPLIDAR->esdata_prev, sizeof(pRPLIDAR->esdata_prev)) != EXIT_SUCCESS)
{
// Failure
printf("A RPLIDAR is not responding correctly. \n");
return EXIT_FAILURE;
}
// Analyze the first data response.
sync = (pRPLIDAR->esdata_prev[0] & 0xF0)|(pRPLIDAR->esdata_prev[1]>>4);
if (sync != START_FLAG1_RPLIDAR)
{
printf("A RPLIDAR is not responding correctly : Bad sync1 or sync2. \n");
return EXIT_FAILURE;
}
ChkSum = (pRPLIDAR->esdata_prev[1]<<4)|(pRPLIDAR->esdata_prev[0] & 0x0F);
// Force ComputeChecksumRPLIDAR() to compute until the last byte...
if (ChkSum != ComputeChecksumRPLIDAR(pRPLIDAR->esdata_prev+2, sizeof(pRPLIDAR->esdata_prev)-1))
{
printf("A RPLIDAR is not responding correctly : Bad ChkSum. \n");
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
So in the above code, we are waiting for the OS read FIFO buffer to show something within 1.5s, checking every 5ms (WaitForRS232Port()). If anything shows up, makes sure to wait to have enough, the size of the payload (GetFIFOComputerRS232Port()).
I'm not sure if it made a difference but we also removed the OS write FIFO buffer by changing it from 0 to FILE_FLAG_NO_BUFFERING:
File: OSComputerRS232Port.h
...
hDev = CreateFile(
tstr,
GENERIC_READ|GENERIC_WRITE,
0, // Must be opened with exclusive-access.
NULL, // No security attributes.
OPEN_EXISTING, // Must use OPEN_EXISTING.
FILE_FLAG_NO_BUFFERING, // Not overlapped I/O. Should use FILE_FLAG_WRITE_THROUGH and maybe also FILE_FLAG_NO_BUFFERING?
NULL // hTemplate must be NULL for comm devices.
);
...
I'm currently implementing a driver for the WINC1500 to be used with an ATMEGA32 MCU and it's getting stuck on this line of "while(!spi_is_tx_empty(WINC1500_SPI));". The code builds and runs but it won't clear what's inside in this function to proceed through my code and boot up the Wifi Module. I've been stuck on this problem for weeks now with no progress and don't know how to clear it.
static inline bool spi_is_tx_empty(volatile avr32_spi_t *spi)
{
// 1 = All Transmissions complete
// 0 = Transmissions not complete
return (spi->sr & AVR32_SPI_SR_TXEMPTY_MASK) != 0;
}
Here is my implementation of the SPI Tx/Rx function
void m2mStub_SpiTxRx(uint8_t *p_txBuf,
uint16_t txLen,
uint8_t *p_rxBuf,
uint16_t rxLen)
{
uint16_t byteCount;
uint16_t i;
uint16_t data;
// Calculate the number of clock cycles necessary, this implies a full-duplex SPI.
byteCount = (txLen >= rxLen) ? txLen : rxLen;
// Read / Transmit.
for (i = 0; i < byteCount; ++i)
{
// Wait for transmitter to be ready.
while(!spi_is_tx_ready(WINC1500_SPI));
// Transmit.
if (txLen > 0)
{
// Send data from the transmit buffer
spi_put(WINC1500_SPI, *p_txBuf++);
--txLen;
}
else
{
// No more Tx data to send, just send something to keep clock active.
// Here we clock out a don't care byte
spi_put(WINC1500_SPI, 0x00U);
// Not reading it back, not being cleared 16/1/2020
}
// Reference http://asf.atmel.com/docs/latest/avr32.components.memory.sdmmc.spi.example.evk1101/html/avr32_drivers_spi_quick_start.html
// Wait for transfer to finish, stuck on here
// Need to clear the buffer for it to be able to continue
while(!spi_is_tx_empty(WINC1500_SPI));
// Wait for transmitter to be ready again
while(!spi_is_tx_ready(WINC1500_SPI));
// Send dummy data to slave, so we can read something from it.
spi_put(WINC1500_SPI, 0x00U); // Change dummy data from 00U to 0xFF idea
// Wait for a complete transmission
while(!spi_is_tx_empty(WINC1500_SPI));
// Read or throw away data from the slave as required.
if (rxLen > 0)
{
*p_rxBuf++ = spi_get(WINC1500_SPI);
--rxLen;
}
else
{
spi_get(WINC1500_SPI);
}
}
Debug output log
Disable SPI
Init SPI module as master
Configure SPI and Clock settings
spi_enable(WINC1500_SPI)
InitStateMachine()
INIT_START_STATE
InitStateMachine()
INIT_WAIT_FOR_CHIP_RESET_STATE
m2mStub_PinSet_CE
m2mStub_PinSet_RESET
m2mStub_GetOneMsTimer();
SetChipHardwareResetState (CHIP_HARDWARE_RESET_FIRST_DELAY_1MS)
InitStateMachine()
INIT_WAIT_FOR_CHIP_RESET_STATE
if(m2m_get_elapsed_time(startTime) >= 2)
m2mStub_PinSet_CE(M2M_WIFI_PIN_HIGH)
startTime = m2mStub_GetOneMsTimer();
SetChipHardwareResetState(CHIP_HARDWARE_RESET_SECOND_DELAY_5_MS);
InitStateMachine()
INIT_WAIT_FOR_CHIP_RESET_STATE
m2m_get_elapsed_time(startTime) >= 6
m2mStub_PinSet_RESET(M2M_WIFI_PIN_HIGH)
startTime = m2mStub_GetOneMsTimer();
SetChipHardwareResetState(CHIP_HARDWARE_RESET_FINAL_DELAY);
InitStateMachine()
INIT_WAIT_FOR_CHIP_RESET_STATE
m2m_get_elapsed_time(startTime) >= 10
SetChipHardwareResetState(CHIP_HARDWARE_RESET_COMPLETE)
retVal = true // State machine has completed successfully
g_scanInProgress = false
nm_spi_init();
reg = spi_read_reg(NMI_SPI_PROTOCOL_CONFIG)
Wait for a complete transmission
Wait for transmitter to be ready
SPI_PUT(WINC1500_SPI, *p_txBuf++);
--txLen;
Wait for transfer to finish, stuck on here
Wait for transfer to finish, stuck on here
The ATmega32 is an 8-bit AVR but you seem to be using code for the AVR32, a family of 32-bit AVRs. You're probably just using the totally wrong code and you should consult the datasheet of the ATmega32, and search for SPI for the AVR ATmega family.
I've got two systems, both running Windows 7. The source is 192.168.0.87, the target is 192.168.0.22, they are both connected to a small switch on my desk.
The source is transmitting a burst of 100 UDP packets to the target with this program -
#include <iostream>
#include <vector>
using namespace std;
#include <winsock2.h>
int main()
{
// It's windows, we need this.
WSAData wsaData;
int wres = WSAStartup(MAKEWORD(2,2), &wsaData);
if (wres != 0) { exit(1); }
SOCKET s = socket(AF_INET, SOCK_DGRAM, 0);
if (s < 0) { exit(1); }
struct sockaddr_in addr;
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_ANY);
addr.sin_port = htons(0);
if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) { exit(3); }
int max = 100;
// build all the packets to send
typedef vector<unsigned char> ByteArray;
vector<ByteArray> v;
v.reserve(max);
for(int i=0;i<max;i++) {
ByteArray bytes(150+(i%25), 'a'+(i%26));
v.push_back(bytes);
}
// send all the packets out, one right after the other.
addr.sin_addr.s_addr = htonl(0xC0A80016);// 192.168.0.22
addr.sin_port = htons(24105);
for(int i=0;i<max;++i) {
if (sendto(s, (const char *)v[i].data(), v[i].size(), 0,
(struct sockaddr *)&addr, sizeof(addr)) < 0) {
cout << "i: " << i << " error: " << errno;
}
}
closesocket(s);
cout << "Complete!" << endl;
}
Now, on first run I get massive losses of UDP packets (often only 1 will get through!).
On subsequent runs, all 100 make it through.
If I wait for 2 minutes or so, and run again, I'm back to losing most of the packets.
Reception on the target system is done using Wireshark.
I also ran Wireshark at the same time on the source system, and found exactly the same trace as on the target in all cases.
That means that the packets are getting lost on the source machine, rather than being lost in the switch or on the wire.
I also tried running sysinternals process monitor, and found that indeed, all 100 sendto calls do result in appropriate winsock calls, but not necessarily in packets on the wire.
As near as I can tell (using arp -a), in all cases the target's IP is in the source's arp cache.
Can anyone tell me why Windows is so inconsistent in how it treats these packets? I get that in my actual application I've just got to rate limit my sends a bit, but I'd like to understand why it works sometimes and not others.
Oh yes, and I also tried swapping the systems for send and receive, with no change in behavior.
Most probably the client is overruning udp send buffer. Maybe while ARP protocol is running to get the target MAC address. You say that you lose datagrams the first run and if you wait 2 minutes or more. Why don't you check with Wireshark what happens in that first run? (If ARP frames are sent/received)
If that is the problem, you could apply one of these 2 alternatives:
1-Before running make sure the ARP entry is there.
2-Send the first datagram, wait 1 sec or less, send the burst
Bugfix update:
As of Jun, 2013 FTDI did acknowledge to me that the bug was real. They have since released a new version of their driver (2.8.30.0, dated 2013-July-12) that fixes the problem. The driver made it through WHQL around the first of August, 2013 and is available via Windows Update at this time.
I've re-tested running the same test code and am not able to reproduce the problem with the new driver, so at the moment the fix seems to be 'upgrade the driver'.
The original question:
I've got an 8 port USB-serial device (from VsCOM) that is based on the FTDI FT2232D chip. When I transmit at certain settings from one of the ports, AND I use the hardware handshaking to stop and start the data flow from the other end, I get two symptoms:
1) The output data sometimes becomes garbage. There will be NUL characters, and pretty much any random thing you can think of.
2) The WriteFile call will sometimes return a number of bytes GREATER than the number I asked it to write. That's not a typo. I ask for 30 bytes to be transmitted and the number of bytes sent comes back 8192 (and yes, I do clear the number sent to 0 before I make the call).
Relevant facts:
Using FTDI drivers 2.8.24.0, which is the latest as of today.
Serial port settings are 19200, 7 data bits, odd parity, 1 stop bit.
I get this same behavior with another FTDI based serial device, this time a single port one.
I get the same behavior with another 8 port device of the same type.
I do NOT get this behavior when transmitting on the built-in serial ports (COM1).
I have a very simple 'Writer' program that just transmits continuously and a very simple 'Toggler' program that toggles RTS once per second. Together these seem to trigger the issue within 60 seconds.
I have put an issue into the manufacturer of the device, but they've not yet had much time to respond.
Compiler is mingw32, the one included with the Qt installer for Qt 4.8.1 (gcc 4.4.0)
I'd like to know first off, if there's anything that anyone can think of that I could possibly do to trigger this behavior. I can't conceive of anything, but there's always things I don't know.
Secondly, I've attached the Writer and Toggler test programs. If anyone can spot some issue that might trigger the program, I'd love to hear about it. I have a lot of trouble thinking that there is a driver bug (especially from something as mature as the FTDI chip), but the circumstances force me to think that there's at least SOME driver involvement. At the least, no matter what I do to it, it shouldn't be returning a number of bytes written greater than what I asked it to write.
Writer program:
#include <iostream>
#include <string>
using std::cerr;
using std::endl;
#include <stdio.h>
#include <windows.h>
int main(int argc, char **argv)
{
cerr << "COM Writer, ctrl-c to end" << endl;
if (argc != 2) {
cerr << "Please specify a COM port for parameter 2";
return 1;
}
char fixedbuf[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
std::string portName = "\\\\.\\";
portName += argv[1];
cerr << "Transmitting on port " << portName << endl;
HANDLE ph = CreateFileA( portName.c_str(),
GENERIC_READ | GENERIC_WRITE,
0, // must be opened with exclusive-access
NULL, // default security attributes
OPEN_EXISTING, // must use OPEN_EXISTING
0, // overlapped I/O
NULL ); // hTemplate must be NULL for comm devices
if (ph == INVALID_HANDLE_VALUE) {
cerr << "CreateFile " << portName << " failed, error " << GetLastError() << endl;
return 1;
}
COMMCONFIG ccfg;
DWORD ccfgSize = sizeof(COMMCONFIG);
ccfg.dwSize = ccfgSize;
GetCommConfig(ph, &ccfg, &ccfgSize);
GetCommState(ph, &(ccfg.dcb));
ccfg.dcb.fBinary=TRUE;
ccfg.dcb.fInX=FALSE;
ccfg.dcb.fOutX=FALSE;
ccfg.dcb.fAbortOnError=FALSE;
ccfg.dcb.fNull=FALSE;
// Camino is 19200 7-O-1
ccfg.dcb.BaudRate = 19200;
ccfg.dcb.Parity = ODDPARITY;
ccfg.dcb.fParity = TRUE;
ccfg.dcb.ByteSize = 7;
ccfg.dcb.StopBits = ONESTOPBIT;
// HW flow control
ccfg.dcb.fOutxCtsFlow=TRUE;
ccfg.dcb.fRtsControl=RTS_CONTROL_HANDSHAKE;
ccfg.dcb.fInX=FALSE;
ccfg.dcb.fOutX=FALSE;
COMMTIMEOUTS ctimeout;
DWORD tout = 10;// 10 ms
ctimeout.ReadIntervalTimeout = tout;
ctimeout.ReadTotalTimeoutConstant = tout;
ctimeout.ReadTotalTimeoutMultiplier = 0;
ctimeout.WriteTotalTimeoutMultiplier = tout;
ctimeout.WriteTotalTimeoutConstant = 0;
SetCommConfig(ph, &ccfg, sizeof(COMMCONFIG));
SetCommTimeouts(ph, &ctimeout);
DWORD nwrite = 1;
for(;;) {
nwrite++;
if (nwrite > 30) nwrite = 1;
DWORD nwritten = 0;
if (!WriteFile(ph, fixedbuf, nwrite, &nwritten, NULL)) {
cerr << "f" << endl;
}
if ((nwritten != 0) && (nwritten != nwrite)) {
cerr << "nwrite: " << nwrite << " written: " << nwritten << endl;
}
}
return 0;
}
Toggler program:
#include <iostream>
#include <string>
using std::cerr;
using std::endl;
#include <stdio.h>
#include <windows.h>
int main(int argc, char **argv)
{
cerr << "COM Toggler, ctrl-c to end" << endl;
cerr << "Flips the RTS line every second." << endl;
if (argc != 2) {
cerr << "Please specify a COM port for parameter 2";
return 1;
}
std::string portName = "\\\\.\\";
portName += argv[1];
cerr << "Toggling RTS on port " << portName << endl;
HANDLE ph = CreateFileA( portName.c_str(),
GENERIC_READ | GENERIC_WRITE,
0, // must be opened with exclusive-access
NULL, // default security attributes
OPEN_EXISTING, // must use OPEN_EXISTING
0, // overlapped I/O
NULL ); // hTemplate must be NULL for comm devices
if (ph == INVALID_HANDLE_VALUE) {
cerr << "CreateFile " << portName << " failed, error " << GetLastError() << endl;
return 1;
}
COMMCONFIG ccfg;
DWORD ccfgSize = sizeof(COMMCONFIG);
ccfg.dwSize = ccfgSize;
GetCommConfig(ph, &ccfg, &ccfgSize);
GetCommState(ph, &(ccfg.dcb));
ccfg.dcb.fBinary=TRUE;
ccfg.dcb.fInX=FALSE;
ccfg.dcb.fOutX=FALSE;
ccfg.dcb.fAbortOnError=FALSE;
ccfg.dcb.fNull=FALSE;
// Camino is 19200 7-O-1
ccfg.dcb.BaudRate = 19200;
ccfg.dcb.Parity = ODDPARITY;
ccfg.dcb.fParity = TRUE;
ccfg.dcb.ByteSize = 7;
ccfg.dcb.StopBits = ONESTOPBIT;
// no flow control (so we can do manually)
ccfg.dcb.fOutxCtsFlow=FALSE;
ccfg.dcb.fRtsControl=RTS_CONTROL_DISABLE;
ccfg.dcb.fInX=FALSE;
ccfg.dcb.fOutX=FALSE;
COMMTIMEOUTS ctimeout;
DWORD tout = 10;// 10 ms
ctimeout.ReadIntervalTimeout = tout;
ctimeout.ReadTotalTimeoutConstant = tout;
ctimeout.ReadTotalTimeoutMultiplier = 0;
ctimeout.WriteTotalTimeoutMultiplier = tout;
ctimeout.WriteTotalTimeoutConstant = 0;
SetCommConfig(ph, &ccfg, sizeof(COMMCONFIG));
SetCommTimeouts(ph, &ctimeout);
bool rts = true;// true for set
for(;;) {
if (rts)
EscapeCommFunction(ph, SETRTS);
else
EscapeCommFunction(ph, CLRRTS);
rts = !rts;
Sleep(1000);// 1 sec wait.
}
return 0;
}
I don't have a good answer yet from FTDI, but I've got the following suggestions for anyone dealing with this issue:
1) Consider switching to a non-FTDI usb-serial converter. This is what my company did, but certainly this isn't an option for everyone (we're putting the chip in our own product). We're using Silicon Labs chips now, but I think there are one or two other vendors as well.
2) Per Hans Passant in the comments - reconsider the use of RTS/CTS signalling. If the writes don't fail due to blocking, then you shouldn't trigger this bug.
3) Set all writes to infinite timeout. Again, no fail due to blocking, no triggering of the bug. This may not be appropriate for all applications, of course.
Note that if pursuing strategy #3, if Overlapped IO is used for writes, then CancelIo and it's newer cousin CancelIoEx could be used to kill off the writes if necessary. I have NOT tried doing so, but I suspect that such cancels might also result in triggering this bug. If they were only used when closing the port anyway, then it might be you could get away with it, even if they do trigger the bug.
If anyone else is still seeing this -- update your FTDI driver to 2.8.30.0 or later, as this is caused by a driver bug in earlier versions of the FTDI driver.
I am using OpenCV in Visual Studio 2010 to track an object, and I am trying to send a value to the Arduino to rotate servos attached to the camera. I am using an Arduino Uno. I have completed the C++ code that tracks the object and determines which direction the camera needs to be rotated, but I am having trouble sending this data to the Arduino. I am currently trying to use an RS-232 cable for this. I am using a Type-B USB cable to program my Arduino and an RS-232 to try to send the data from Visual Studio to the Arduino. Here is my code for the Visual Studio serial communication:
int portspeed(int centerpix, int xmid)
{HANDLE hDevice = CreateFile(L"COM5",GENERIC_READ | GENERIC_WRITE,FILE_SHARE_READ | FILE_SHARE_WRITE,NULL,OPEN_EXISTING,0,0);
DCB lpTest;
GetCommState(hDevice,&lpTest);
lpTest.BaudRate = CBR_9600;
lpTest.ByteSize = 8;
lpTest.Parity = NOPARITY;
lpTest.StopBits = ONESTOPBIT;
SetCommState(hDevice,&lpTest);
DWORD btsIO;
if (centerpix<xmid)
{
char test[] = "2";
WriteFile(hDevice,test,strlen(test),&btsIO,NULL);
cout << "Turn right " << test << endl;
}
else
{
char test[] = "3";
WriteFile(hDevice,test,strlen(test),&btsIO,NULL);
cout << "Turn left " << test << endl;
}
return 0;
}
On the Arduino code side I have this, which I am using to attempt to light two different LEDS to see if the program is able to correctly communicate which direction it needs to rotate:
int incomingByte = 0; // For incoming serial data
void setup()
{
Serial.begin(9600); // Opens serial port, sets data rate to 9600 bit/s
}
void loop()
{
// Send data only when you receive data:
if (Serial.available() > 0)
{
incomingByte = Serial.read();
if (incomingByte==50) //if =2
analogWrite(9,100);
else
analogWrite(9,0);
if (incomingByte==51) //if =3
analogWrite(10,50);
else analogWrite(10,0);
delay(3000);
}
else
analogWrite(9,255);
}
My interpretation is that I need to start the C++ program (which continuously sends the data over the serial communication), and then attach the TX pin from the RS-232 into the RX pin (digital 0) on the Arduino. When I try to upload the program to the Arduino I am given an error,
avrdude: stk500_getsync(): not in sync: resp=0x00
This only occurs when I have a wire going into the RX pin, even if this wire is not connected to anything. I believe that this error occurs because the RX is looking for an input with a baud rate of 9600, but it still gives me this error when the C++ program is running and sending the data with a rate of 9600.
How can I send a value from a Visual Studio project doing real time image processing on a laptop to an Arduino via serial communication?
Speaking as someone with limited Win32 experience (more of a .NET guy, really), I think your problem may be in write buffering.
By default, writes to a file or port are buffered in memory. Perhaps the write is never getting sent to the port as you are never closing the file handle nor calling [FlushFileBuffers][3].
Try adding this prior to return 0;:
//After a time, sensitive write
FlushFileBuffers(hDevice);
//or, more properly for the end of the program.
CloseHandle(hDevice);