Data Transmission Timing; Figure 5.4A Data Transmission Timing (Compatible Mode) - Fujitsu PrintPartner 12V Product Description

5.2.3 Data transmission timing

The PrintPartner 12V 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 iddle 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

Figure 5.4a Data transmission timing (compatible mode)

* The values of T4 and T6 are assumed that the host uses ITTL for
its input circuits.
Tl, T2,T3 > 0.5 us
T4 < 0.5 us (*)
T5,T7 = 0 us
T6 = 0.5 us (*)
5-5