CM108B recognition issue and infor missing issue
CM108B IC has built-in 1.5k ohm pull-up, please remove the external 1.5k ohm and test again.
Thanks & B.R.
OK. I will remove the 1.5K resisitor and try again. But why an aditional 1.5K resisitor on DP can pullup the DM?
According to the USB specification, the Full Speed device must have a pull-up 1.5k ohm on DP, and DM does not need to do any actions on the circuit. "DM pull down" does not meet USB specification, we can't predict what will happen. Thanks.
Thanks for reminding. We are doing the test now ( without pullup and pulldown on DP & DM, use CM108B internal pullup )
Could you please help us analysis the data missing issue? 18 bytes data only got 8 bytes. When 1st time send the command " Get Descriptor" ,we can not get full data. Please see JPG for detail.