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CFA631 Dane(HTML) 59 Page - Crystalfontz America, Inc.
CRYSTAIFONTZ [Crystalfontz America, Inc.]
CFA631 Datasheet(Arkusz danych) 59 Page - Crystalfontz America, Inc.
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Data Sheet Release 2014-11-17
CFA631 Intelligent Display Modules
The default GPIO mode uses PWM and a suitable current limiting resistor to control the LEDs on the front of the display
module. They can be turned on and off and even dimmed under host software control. With suitable external circuitry,
the GPIOs can also be used to drive external logic or power transistors.
The CFA631 continuously polls the GPIOs as inputs at 32 Hz. The present level can be queried by the host software at
a lower rate. The CFA631 also keeps track of whether there were rising or falling edges since the last host query (subject
to the resolution of the 32 Hz sampling). This means that the host is not forced to poll quickly in order to detect short
events. The algorithm used by the CFA631 to read the inputs is inherently “debounced”.
The GPIOs also have “pull-up” and “pull-down” modes. These modes can be useful when using the GPIO as an input
connected to a switch since no external pull-up or pull-down resistor is needed. For instance, the GPIO can be set to pull
up. Then when a switch connected between the GPIO and ground is open, reading the GPIO will return a “1” When the
switch is closed, the input will return a “0”.
Pull-up/pull-down resistance values are approximately 5k
Ω. Do not exceed current of 25 mA per GPIO.
The GPIO configuration is one of the items stored by the command 4 (0x04): Store Current State As Boot State (Pg. 39).
type: 0x22 = 34
2 bytes to change value only
3 bytes to change value and configure function and drive mode
data: index of GPIO to modify on optional SCAB’s connector when using CFA631+SCAB+WR-
0 = GPIO = J8, Pin
1 = GPIO = J8, Pin
12 (default is ATX Host Power Sense)
2 = GPIO = J8, Pin
9 (default is ATX Host Power Control)
3 = GPIO = J8, Pin
10 (default is ATX Host Reset Control)
4 = GPIO = J9, Pin
13 (default is DOW I/O--has 1k
Ω hardware pull-up)
5-255 = not accessible
Please note: Future versions of this command on future hardware display modules may accept
additional values for data, which would control the state of future additional GPIO
data = Pin output state (actual behavior depends on drive mode):
0 = Output set to low
1-99 = Output duty cycle percentage (100 Hz nominal)
100 = Output set to high
101-254 = invalid
GPIO has R8 (5.6k) in series by default. If you need GPIO to be a low impedance output, please
replace R8 with a 0Ω resistor.
The GPIO pins may also be used for ATX control through the optional SCAB’s 7-pin connector and
WR-DOW-Y17 temperature sensing through the SCAB’s DOW header. By factory default, the GPIO
output setting, function, and drive mode are set correctly to enable operation of the ATX and DOW
functions. The GPIO output setting, function, and drive mode must be set to the correct values
in order for the ATX function to function properly, Our free demonstration software cfTest may be
used to easily check and reset the GPIO configuration to the default state so the ATX and DOW func-
tions will work.
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