67 Programmable Hardware Manual (PHM)
© Tibbo Technology Inc.
4.4.1.1
Serial Port and General-purpose I/O Lines
The EM510 has ten I/O lines: eight general-purpose I/O lines GPIO0-7, plus TX and
RX lines of the serial port.
I/O lines of the EM510 are NOT 5V-tolerant. The maximum load current for each
line is 10mA.
GPIO0 and GPIO1 lines double as interrupt inputs INT0 and INT1. GPIO1, GPIO3, and
GPIO4 can optionally be used to connect an external flash IC. This IC is required if
you want to use the flash disk (fd.) object. GPIO5, GPIO6, and GPIO7 can optionally
be used to connect to the WA2000 Wi-Fi/BLE add-on. The add-on is required if you
want to use the Wi-Fi (wln.) and BLE (bt.) objects.
The serial port has four I/O lines: RX, TX, CTS, and RTS. TX and RX lines belong
exclusively to the serial port and are separate from the GPIO lines. CTS and RTS
lines do not exist independently. Rather, either GPIO0/INT0 or GPIO1/INT1 can be
selected to serve as the CTS line, while any of the GPIO0-7 lines can be selected to
serve as the RTS line. This is done through ser.rtsmap and ser.ctsmap properties of
the serial (ser.) object.
The serial port of the EM510 can work in one of the three modes: UART, Wiegand,
or clock/data (TX, RX, CTS, and CTS lines have different names and functions in the
Wiegand and clock/data modes).
A simplified structure of one I/O line of the EM510 is shown on the circuit diagram
below. Each line has an independent output buffer control. When the EM510 powers
up, all its I/O lines have their output buffers tri-stated (in other words, all I/O lines
are configured as inputs). With the exception of several cases listed below, you
need to programmatically enable the output buffer of a GPIO line if you want this
line to become an output.
Cases when IO lines are controlled automatically
Direction configuration of TX and RX lines happens automatically when the serial
port is in the UART mode: Setting ser.mode= 0- PL_SER_MODE_UART and
ser.enabled= 1- YES for the first time automatically configures the TX line as an
output, while the RX line remains an input. The same is not true for Wiegand and
clock/data modes. Once the serial port is enabled, you lose the ability to control the
TX line (set it HIGH or LOW) programmatically. Disabling the serial port (ser.enabled=
0- NO) does not alter the direction configuration of the TX line.
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