EPP_Slave Extended Parallel Port
Interface Slave Core
The Enhanced Parallel Port (EPP) interface is a standard protocol (IEEE 1284) used in Personal Computers. The EPP protocol, permits bi-directional data transfer between the PC and a peripheral device. Data transfer rates vary between 500 Kbytes/s and 2000 Kbytes/s, depending on the processing power of the PC and the implementation of the EPP master in the PC. The EPP slave is ideal to interface peripherals with a PC easily and with low cost.
The EPP slave core was carefully designed to provide reliable communication. A prototype peripheral using the core was developed and used during the testing procedures. Many hours were spent to improve the core and optimize the VHDL code, so as to achieve a reliable and fast communication between the core and the PC. The EPP slave core works reliably without external discrete components when a good quality parallel (EPP) cable is used. Adding Schmitt trigger inverters to the input signals increases the reliability of the communication dramatically.
From the peripheral side, the EPP_Slave core uses a generic microprocessor bus interface and the peripheral sees the PC through the parallel port as an external microprocessor. The core provides to the peripheral, input and output 8-bit data busses, an 8-bit address bus and read / write strobes.
The EPP interface doesn’t support interrupts. The PC always plays the role of the master and initiates read or write transactions
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