Serial Port Complete - Latest Microcontroller projects

Chapter 15


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Figure 15-2 shows the pin functions for the FT245R USB FIFO. The USB

interface and power options are the same as for the FT232R. But instead of an

asynchronous serial port, the chip has an 8-bit, bidirectional parallel data bus

with status and control pins that control reading and writing to the buffer. (A

FIFO is a buffer whose contents are read in the same order as they were stored.

In other words, the first byte written to the buffer is the first byte read from the

buffer.) On receiving data on the parallel port, the chip sends the data to the

USB host. On receiving data from the USB host, the chip makes the data avail-

able to read at the parallel port.

The status and control signals are named from the perspective of the external

CPU or microcontroller that interfaces to the chip. The RXF# output is low

Figure 15-2: The FT245R converts between USB and parallel data.