IPC@CHIP DB54
Hardware Manual V1.1 [04.10.2007]
4.4 SW18 - Power-fail button
Pressing the PFI button (SW18) emulates a power-fail event if the Power-fail function is enabled in the SC23, and
calls a power-fail software routine. This routine can write data to the Flash memory area of the SC23. The Power-
fail function must be software-enabled (CHIP.INI or software interrupt). Using the PIO9 function of the PFI/PIO9
signal, the PFI button can also be used as a push-button for input.
4.5 SW19 - Reset button
Power-on reset and the reset button (SW19) generate a low active reset pulse for the SC23 processor.
4.6 LED’s and DIP switch
For digital input and output simulation
The DIP-switch is connected to an I2C I/O port expander (PCF8574A). It is coded to the I2C base
address 72hex. A switch in the ON position will read out logic 0, and a switch in the OFF position will
read out logic 1. Using the I2C port expander it ispossible to have a practical expansion of input and
output signals for the SC23.
switch
PCF8574A
I/O expander
BIT7 D7
BIT6 D6
BIT5 D5
BIT4
D4
BIT3
D3
BIT2
D2
BIT1
D1
BIT0
D0
The LED’s are connected to an I2C I/O port expander (PCF8574A). It is coded to the I2C base
address 70hex. To light up an LED you have to write logic 0 to the corresponding port bit, and to
switch the LED off you need a logic 1 at the port bit.
LED
PCF8574A
I/O expander
BIT7 D7
BIT6 D6
BIT5 D5
BIT4
D4
BIT3
D3
BIT2
D2
BIT1
D1
BIT0
D0
©2000-2008 Beck IPC GmbH
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