35
Programmable Hardware Manual (PHM)
© Tibbo Technology Inc.
73
(1,2,4)
GPIO49
General-purpose I/O line 49 (does not belong to
any 8-bit port).
74
(4,5)
SPIDI
SPI, data in [no longer in use].
75
(1,2,4)
GPIO50
General-purpose I/O line 50 (does not belong to
any 8-bit port).
76
(4,5)
SPIDO
SPI, data out [no longer in use].
77
(1,2,4)
GPIO51
General-purpose I/O line 51 (does not belong to
any 8-bit port).
78
(1,2,4,5)
SPICLK
SPI, clock line [no longer in use].
79
(1,2,4)
GPIO52
General-purpose I/O line 52 (does not belong to
any 8-bit port).
80
(1,2,4)
GPIO53
General-purpose I/O line 53 (does not belong to
any 8-bit port).
Notes:
1. This line is 5V-tolerant and can be interfaced to 5V CMOS devices directly.
2. This line can be mapped to serve as an RTS/Wout/cout line of a serial port
(provided that this does not interfere with any other function).
3. This line can serve as a CTS/W0&1in/cin line of a serial port (provided that this
does not interfere with any other function).
4. This pin is on the
port (formerly known as "SPI port"). "-A" option
device modification has the connector header soldered in and "available" to the
host PCB. "T" option devices have a female connector. Other EM1000 versions do
not have any connector installed.
5. The SPI lines are no longer used. Our current wireless add-on modules, such as
the WA2000, rely on GPIO49~53 for communicating with add-on devices. SPIDI,
SPIDO, and SPOCLK lines should never be connector to.
4.2.2.1
General-purpose I/O Lines
The EM1000 has 54 general-purpose I/O lines (GPIO0 - GPIO53). All lines are 3.3V,
CMOS, 5V-tolerant lines. Maximum load current for each I/O line is 10mA. 49 of
these lines are always available. Remaining 5 lines are located on the
. This connector is "available" to the host PCB only on option "-A"
EM1000 devices.
40 of the I/O lines are combined into five 8-bit ports.
The simplified structure of one I/O line of the EM1000 is shown on the circuit
diagram below. Each line has an independent output buffer control. When the
EM1000 powers up all its I/O lines have their output buffers tri-stated (in other
words, all I/O lines are configured as inputs). You need to explicitly enable the
output buffer of a certain I/O line if you want this line to become an output.
Many I/O lines of the EM1000 also serve as inputs or outputs of special function
modules, such as serial ports. Majority of those lines need to be correctly configured
as inputs or outputs -- this won't happen automatically. Several lines -- such as TX
and RX lines of the serial port when in the UART mode -- are configured as outputs
and inputs automatically when the serial port (or some other hardware block) is
enabled. For details see "Platform-dependent Programming Information inside the
EM1000 platform documentation (TIDE, TiOS, Tibbo BASIC, and Tibbo C Manual).