Fujitsu C145-C037-01EN manual 4a Data transmission timing compatible mode

5.2.3 Data transmission timing

The PrintPartner 20W uses a bi-directional parallel interface complying with IEEE 1284. This interface is also compatible with the conventional Centronics interface. Data transfer from host to printer is performed according to Centronics standard, called compatible mode. Data transfer from printer to host is performed according to the IEEE 1284 standard, called nibble mode.

In compatible mode, the printer receives data from the computer in handshaking mode based on the Busy and Acknowledge signals from the printer and the Data Strobe signal from the computer. For the Data Strobe and Acknowledge signals, the timing of the Busy signal must be as shown in the compatible mode of Figure 5.4a.

To send data from the printer to the host, the interface enters the nibble mode where data is sent in units of four bits (nibble) using four output signal lines as data paths. The data transfer sequence in nibble mode involves negotiation phase, reverse idle phase, reverse data transfer phase, and termination phase. Figure 5.4b shows the reverse data transfer phase where data is sent.

Data 1 to 8

Data Strobe

Busy

Acknowledge

T4

(*)

T1 T2 T3 T5 T6 (*) T7

*The values of T4 and T6 are assumed that the host uses ITTL for its input circuits.

T1, T2, T3 > 0.5 μs

T4 < 0.5 μs (*)

T5, T7 = 0 μs

T6 = 0.5 μs (*)

Figure 5.4a Data transmission timing (compatible mode)

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