Star Micronics lC-10, Technical Manual

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THEORY OF OPERATION
Fig. 2-5 Timing Chart of Non-EOI Handshake Mode
Fig. 2-6 Timing Chart of EOI Handshake Mode
(1) Non-EOI handshake
This is a regular data transmission handshake.
1.
The host computer acknowledges that the DATA line is low (data reception is completed), raises the CLK, and
notifies the printer that the host computer is ready to send (data or commands).
2. The printer sends information to the host computer by raising the DATA line to show that the printer is ready
to receive more data.
3. The host computer sends information to the printer that data is available after the next raising of the CLK, by
lowering the CLK.
4. After storing data, the host computer indicates that the data is available by raising the CLK.
The printer reads the data at the rising edge of the CLK. Then the host computer lowers the CLK and opens
the DATA line, acknowledging that the printer is in READY mode (DATA line is high), and moves to the next
bit handshake.
5. Sending 8-bit data is the same as above. When transmission is completed, the printer sends information to the
host computer that the receiving of data is finished by lowering the DATA line.
(2) EOI handshake
This handshake is used to show that the next data bytes are the last data.
1.
The host computer acknowledges that the DATA line is LOW (receiving data is finished), and sends
information to the printer that the host computer is ready to send data (including commands) by raising the
CLK.
2. The printer sends information to the host computer that the printer is ready to receive data by raising the DATA
line.
At the rising edge the 500
µ
s timer starts.
(Until now this has been operating the same as the Non-EOI handshake.) From the starting of the timer, the
host computer keeps the CLK high for more than 500
µ
s to indicate EOI.
3. If the CLK does not fall within 500
µ
s, the printer acknowledges the EOI, and lowers the DATA line to LOW.
4. The printer sends information to the host computer that it is ready to receive data by raising the DATA line
again.
To send 8-bit data, follow the preceding Non-EOI handshake procedure.