Quality RTOS & Embedded Software

 Real time embedded FreeRTOS RSS feed 
Quick Start Supported MCUs PDF Books Trace Tools Ecosystem


lwIP_Demo_Rowley_ARM7 and CDC receiving byte

Posted by Steve MULLER on August 13, 2008

I am new to FreeRTOS. Seems to be a great OS.
I try to modify the demo code to have a simple ping-pong over the CDC.

I add the following lines to several files :

* lwIP_Demo_Rowley_ARM7\USB\USB-CDC.c:262
unsigned vUSBReceiveByte( portCHAR * cByte )
if ( uxQueueMessagesWaiting( xRxCDC ) != 0 )
xQueueReceive( xRxCDC, cByte, usbNO_BLOCK );
return 1;
return 0;

* lwIP_Demo_Rowley_ARM7\USB\USB-CDC.h:99
unsigned vUSBReceiveByte( portCHAR * cByte );

* lwIP_Demo_Rowley_ARM7\main.c:313
if ( vUSBReceiveByte( &cTxByte ))
vUSBSendByte( cTxByte );

With this code the OS seems to be completly frozen.

What is false in my code ? And why ?

Thanks in advance.


P.S. : I use the V5.0.2 of FreeRTOS.

RE: lwIP_Demo_Rowley_ARM7 and CDC receiving byte

Posted by Dave on August 13, 2008
I think this demo uses an idle task hook function or something similar to continuously send characters in the background. Did you remove this code first? Just setting configUSE_IDLE_HOOK to 0 in FreeRTOSConfig.h might be enough.

RE: lwIP_Demo_Rowley_ARM7 and CDC receiving byte

Posted by Steve MULLER on August 13, 2008

Currently, I use this hook to handle the Queue over vUSBReceiveByte().
I removed the code who continuously send characters.



[ Back to the top ]    [ About FreeRTOS ]    [ Privacy ]    [ Sitemap ]    [ ]

Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.

Latest News

NXP tweet showing LPC5500 (ARMv8-M Cortex-M33) running FreeRTOS.

Version 10.1.1 of the FreeRTOS kernel is available for immediate download. MIT licensed.

View a recording of the "OTA Update Security and Reliability" webinar, presented by TI and AWS.


FreeRTOS and other embedded software careers at AWS.

FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Espressif ESP32

IAR Partner

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers


STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

OpenRTOS and SafeRTOS

Xilinx Microblaze and Zynq partner