C541U_99 Datasheet, PDF (122/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

On-Chip Peripheral Components
C541U
6.4.8.4 Interrupt Transfer
The direction of this transfer is always from the device to the host. The usage is intended for device
polling with programmable rate from 10 ms to 255 ms. A no acknowledge handshake (NACK) is
automatically returned to the host, if the device has currently no interrupt data to transfer.
Software is required to set up the data packet in the USBDRn registers, to set the LEN bit field
according to the data length and to set the TYPE bit field to either 0110_B (for EP1 interrupt endpoint)
or 0111_B (for EP2 interrupt endpoint).
Semiconductor Group
6-77
1999-04-01