Xerox FaxCentre F12, Service Manual

Page: 93 / 380

Circuit Description
WorkCentre Pro 412, FaxCentre F12 & 3/03 5-55
WorkCentre M15/M15i
ECP Hardware Handshaking Timing (forward)
1. The host places data on the data lines and indicates a data cycle by setting nAUTOFD.
2. Host asserts nSTROBE low to indicate valid data.
3. Peripheral acknowledges host by setting BUSY high.
4. Host sets nSTROBE high. This is the edge that should be used to clock the data into the Peripheral.
5. Peripheral sets BUSY low to indicate that it is ready for the next byte.
6. The cycle repeats, but this time it is a command cycle because nAUTOFD is low.
ECP Hardware Handshaking Timing (forward)
1. The host request a reverse channel transfer by setting nINIT low.
2. The peripheral signals that it is OK to proceed by setting PE low.
3. The peripheral places data on the data lines and indicates a data cycle by setting BUSY high.
4. Peripheral asserts nACK low to indicate valid data.
5. Host acknowledges by setting nAUTOFD high.
6. Peripheral sets nACK high. This is the edge that should be used to clock the data into the host.
7. Host sets nAUTOFD low to indicate that it is ready for the next byte.
8. The cycle repeats, but this time it is a command cycle because BUSY is low.