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MQX CDC ACM Communication

Question asked by kiran kunnath on Oct 29, 2013
Latest reply on Dec 7, 2013 by mauricioscalerandi

Hello All,

     I need to connect a USB CDC ACM modem device to the MCU. I have to send and receive data packets to and from modem through USB interface. My modem device is having a UART interface for controlling the modem with AT commands. I have gone through MQX example for USB host CDC device. In this example, as per my understanding, after reading data from UART hyper-terminal, it will  write to the device through USB interface. And after reading data from the device through USB interface, it will display the data in hyper-terminal by UART.

For me i need to send a data buffer to modem. For this can i pass data "myBuffer" directly to the below API in the cdc_serial.c,without using UART APIs?


fwrite( myBuffer, sizeof(buffer[0]), num, f_usb);in the cdc_serial.c ?


Similarly For reading data from modem to my local buffer, can i directly use the API


fread(myBuffer, 1, sizeof(myBuffer) / sizeof(myBuffer[0]) - num, f_usb);?


All the enumeration should be done with this example code cdc_serial.c?


I don't have much idea about the CDC ACM communication.

One  basic question,

What is the relation between CDC ACM device and USB COM communication? I went through different documents, still i have some confusion.

When i connect a cdc device to the host MCU, the device will be considered as a USB device or UART device?


Please help me to solve this issue.


Thanks in advance,