PORTS Forum
Ports and Interfaces => USB => Topic started by: lcpoon on September 04, 2012, 11:10:09 am
-
(a) I have no problem to send the data to the device.
(b) When reading the data from the device, this problem occurred.
- Before I read the data, I am using control transfer to query for the device information such as manufacturer, product and serial number. After that, I read the data using bulk transfer. The retured data is overwrite by the serial number in control transfer.
- If I read the data directly without control transfer before, the returned data is OK.
-
If the device is returning the serial number instead of the desired data, look at the buffers in your device firmware. Be sure the firmware is placing the data to send in the bulk-transfer buffer, and be sure that the control transfers aren't using the same buffer and thus overwriting the bulk-transfer data.