paulbearne04
Resolved by ptp!
Hi i am having problems using the Uart 0 with the sdk c# on my ez-b v4 i am writing a standalone app as well as a plugin for my inmoov bot, as i only have one ez-b v4 (limited funds) i am using an stm32F429 discovery board i had lying around to operate the additional servos and neopixel ring. The F429 disco board is working fine and i can send a simple command from the ez-b the protocol is just 4 bytes [0xFE][command byte][servonum byte][value byte] and works fine at 115200 F429 recieves the commands without any problems but i then send back either the same 4 bytes to acknowledge a set command or with a changed value byte if requesting a value from the F429 i have the following code set up in C# to wait for the response but it always returns the same value of 239 0xef in both my standalone version and the plugin version the F429 is sending correctly as i have connected it to an arduino , Nulceo stm32F746 and Nucleo stm32F401 and they all receive the 4 bytes correctly. i suspect i am doing something wrong as the _ezb.Uart.UARTExpansionAvailableBytes always seems to return 4086 once i send it data from the F429 I have been struggling with this for a couple of days now so any help would be appreciated am i using the right command to read the data?
private byte[] waitforresponse(int port) { // start timeout timer timeoutTimer.Enabled = true; TimedOut = false; // here to debug uart rx problem // bytes = 0 first time though the loop int bytes = _ezb.Uart.UARTExpansionAvailableBytes(port); while ((_ezb.Uart.UARTExpansionAvailableBytes(port) < 4) && (TimedOut == false)) {
Application.DoEvents();
}
timeoutTimer.Enabled = false;
// here to debug uart rx problem
// bytes = 0 first time though the loop
bytes = _ezb.Uart.UARTExpansionAvailableBytes(port);
if (TimedOut == false)
{
// original code return 4 bytes all with 239 0xEF
//byte[] data = _ezb.Uart.UARTExpansionRead(port, 4);
// added this for debug
// reads 4086 bytes all of the same value 239 0xEF
byte[] data = _ezb.Uart.UARTExpansionReadAvailable(port);
return data;
}
else
{
return null;
}
}
@paulbearne04,
if you have a remote device connected (uart) sending bytes, EZ-B will process the bytes from the UART FIFO and will keep it in a fixed buffer .
buffer size = 5000 bytes https://synthiam.com/Community/Questions/5403
If you don't execute UARTExpansionRead or UARTExpansionReadAvailable the data will accumulate in the buffer, and then buffer will overflow (losing old data or not keeping up with the new data).
Can you check the remote side logic if is not generating the data, while waiting for an ACK (your software logic) from the EZB side ?
Can you post the Arduino/STM32 code ?
Thanks for the reply ptp
That's what i put the 4086 bytes available down to but the code is break pointed at remote and in VS so could only ever send once , my thoughts also as the number it shows its buffer full of it 0xEF and my remote which is nibbles reversed of the sof character sent at the start of the data packet 0xFE which i think may just be a red heron also when i collect the data and look at it using UARTExpansionReadAvailable it is just full of 0xEF. I can see on the lcd the command is received only once thats not to say that MBED code is not messed up lower down but the keil debugger stops the code when a breakpoint is hit so i'm pretty certain it only gets there once. while typeing i realised i haven't tried just sending a byte from the remote so will try that later
code for remote
is pretty simple Serial device(PC_10,PC_11);
void ParseCommand() { uint8_t Text[30]; uint8_t txbuf[4] = {buf[0],buf[1],buf[2],buf[3]}; int i;
}
// serial uart Rx ISR void callback() { uint8_t inchar; // while the fifo has data loop collecting it while(device.readable()) { // read the first character this will also clear the interupt inchar = device.getc(); // see if we have sof character if( inchar == 0xfe) { buf[0] = 0xfe; startbyte = true; bufcount = 1; } else { if (startbyte) { // received a sof so start getting command and data buf[bufcount++] = inchar; if (bufcount >= 4) { bufcount=0; // we have full command packet so act on it ParseCommand(); // reset sof received flag ready for next command startbyte = false; } }
}
@paulbearne04,
Use code tags e.g. [ code ] and [ /code ] to format the code:
I added some code to help the troubleshooting:
Let's check simple things in sequence:
3 wires to connect both devices: rx, tx, gnd
you have somewhere serial format & baud: device.format(8, Serial::None, 1); device.baud(115200); Try to change to a slow speed e.g. 9600
Somewhere in your c# code you have: UARTExpansionInit(0, 115200);
Your c# code does the following: connects to the EZB wait a few seconds (or connect event) executes UARTExpansionInit (... ) executes UARTExpansionReadAvailable (...)
if you call UARTExpansionAvailableBytes(...) what is the return value ?
do you get any feedback in the LCD after the above points?
Send a command or dummy command, does the LCD reports the command ?
if you execute UARTExpansionAvailableBytes (...) do you get 4 bytes reported ?
Thanks Ptp i'll add the code and i should of put default case tomorrow pm as evening here now and have a hospital appiontment tomorrow am. Thanks for tip on the tags
i have tried 1 2 and 3 , 4 i use onconnect but do init later when i'm using the comms 5 it reads 0 on first call then 4086 after that. 7 lcd does report the command being received one the functions in c# code is to send servo config min max speed and step which get reported correctly on the lcd so i dont think its a timing issue. i'll check 8 as at the moment it will come out of the loop on timeout or any number of characters as long as its above 4.
PTP is rock'n the question - however, i have a question about why you're using Application.DoEvents()?
Hi DJ Sures yes just yielding to allow other parts of the app to update display etc if for any reason the Comms response doesn't arrive as it will wait in the while loop for the timeout to occur and the the app got a bit jerky if comms not connected.
@paulbearne04,
two questions:
@paulbearne04,
I created a sample mbed program to test the serial communication between a STM32F01 and EZB v4.
the message protocol is simple and you can use ARC's Serial Terminal to test the interaction.
the code is simple, no bullet proof neither is rocket science
i hope it can help.