Zebra 01407-000 Manual Do Utilizador
Interfaces
Parallel Interface (TTP 1020)
Parallel Interface (TTP 1020)
72
P1003643-001
TTP 1020™/TTP 1030™ Technical Manual
03/03/2009
Figure 17 • Basic Negotiation Sequence
1.
The host places the requested extensibility byte on the data lines
2.
The host then sets _SelectIn high and _AutoFeed low to indicate a negotiation sequence.
3.
A 1284 peripheral will respond by setting _Ack low, and _Error, PE, and Select high. A
non-1284 peripheral will not respond.
non-1284 peripheral will not respond.
4.
The host sets _Strobe low. This is used to strobe the Extensibility byte in to the peripheral.
5.
The host then sets _Strobe and _AutoFeed high to signal to the peripheral that it
recognizes it as a 1284 device.
recognizes it as a 1284 device.
6.
The peripheral responds by setting PE low, _Error low if the peripheral has reverse
channel data available, and Select high if the requested mode is available, or Select low if
the requested mode is not available.
channel data available, and Select high if the requested mode is available, or Select low if
the requested mode is not available.
7.
The peripheral now sets _Ack high to signal that the negotiation sequence is over and the
signal lines are in a state compatible with the request mode.
signal lines are in a state compatible with the request mode.
This was just an introduction to the use of IEEE-1284 parallel ports. How to select and use the
different modes is explained further in the IEEE-1284 standards.
different modes is explained further in the IEEE-1284 standards.