Does fread() have a timeout feature (MQX4.2)?

[markkalior]

I am reading a response from a perpherial, but some timesome I get no response at all.   If the driver is blocking, then the driver waits forever.   If the driver is non-blocking, then the application must loop on fread() for whatever the timeout period is. 

Is there feature of fread() or some other read function, that waits for a response until the timeout period has expired (and becomes non-blocking)?

[soledad]

Hello Mark,

Which driver are you using? could you please post the code you are using?

Regards

Soledad

[markkalior]

UART driver.

uartfd = fopen("ittya:", (void*)(IO_SERIAL_RAW_IO | IO_SERIAL_NON_BLOCKING));

result = fwrite(&command, length, uartfd);

result = fread(&response, length, uartfd);

If the driver is BLOCKING, and the perpherial doesn't have a response, the fread will wait forever.

if the driver is NON_BLOCKING, then the driver simply get the data if present (does not wait at all).

Is there a flag that BLOCKS for a certain time (i.e. timeout), then returns?   The application can then determine if there was a timeout or data.

Linux does allow this behavior.   Does MQX?

[danielchen]

Hi Mark:

unfortunately there is not a time out flag in current MQX uart driver.  we support the following open flags, please refer to  mqx\source\io\serial\serial.h

#define IO_SERIAL_RAW_IO             (0)

#define IO_SERIAL_XON_XOFF           (0x01)

#define IO_SERIAL_TRANSLATION        (0x02)

#define IO_SERIAL_ECHO               (0x04)

#define IO_SERIAL_HW_FLOW_CONTROL    (0x08)

#define IO_SERIAL_NON_BLOCKING       (0x10)

#define IO_SERIAL_HW_485_FLOW_CONTROL (0x20)

Regards

Daniel