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Do I need a 1.5K pullup on USB D+ line?

Question asked by o_tech on Apr 22, 2017
Latest reply on Apr 23, 2017 by wolff.roger

Do i need a pullup 1.5K resistor on D+ for USB Full Speed when the USB is configured as a Device (peripheral)? I recently build a custom circuit board without the 1.5K pullup and the PC didn't detect it?  unfortunately I damaged the circuit board so i cannot retest it with the 1.5K resistor.


My connections:


D-  = PA11 (with 22 ohm resistor in series),

D+ = PA12 (with 22 ohm resistor in series), 

V_USB is not configured.


I use the same code on my STM32F407 discovery board and it  works fine therefor it cannot be the code. I am using the HAL lib with STMCube).