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The PCF8574/74A provides general-purpose remote I/O expansion via the two-wire bidirectional I2C-bus (serial clock (SCL), serial data (SDA)).The devices consist of eight quasi-bidirectional ports, 100 kHz I2C-bus interface, three hardware address inputs and interrupt output operating between 2.5 V and 6 V. The quasi-bidirectional port can be independently assigned as an input to monitor interrupt status or keypads, or as an output to activate indicator devices such as LEDs. System master can read from the input port or write to the output port through a single register. The low current consumption of 2.5 uA (typical, static) is great for mobile applications and the latched output ports directly drive LEDs.The PCF8574 and PCF8574A are identical, except for the different fixed portion of the slave address. The three hardware address pins allow eight of each device to be on the same I2C-bus, so there can be up to 16 of these I/O expanders PCF8574/74A together on the same I2C-bus, supporting up to 128 I/Os (for example, 128 LEDs).The active LOW open-drain interrupt output (INT) can be connected to the interrupt logic of the microcontroller and is activated when any input state differs from its corresponding input port register state. It is used to indicate to the microcontroller that an input state has changed and the device needs to be interrogated without the microcontroller continuously polling the input register via the I2C-bus.The internal Power-On Reset (POR) initializes the I/Os as inputs with a weak internal pull-up 100 uA current source. PCF8574 is used in LED signs and displays, servers, key pads, industrial control, medical equipment, PLC, cellular telephones, mobile devices, gaming machines and instrumentation test measurement.
LibDriver PCF8574 is a full function driver of PCF8574 launched by LibDriver.It provides I/O writing, I/O reading and other functions. LibDriver is MISRA compliant.
/src includes LibDriver PCF8574 source files.
/interface includes LibDriver PCF8574 IIC platform independent template.
/test includes LibDriver PCF8574 driver test code and this code can test the chip necessary function simply.
/example includes LibDriver PCF8574 sample code.
/doc includes LibDriver PCF8574 offline document.
/datasheet includes PCF8574 datasheet.
/project includes the common Linux and MCU development board sample code. All projects use the shell script to debug the driver and the detail instruction can be found in each project's README.md.
/misra includes the LibDriver MISRA code scanning results.
Reference /interface IIC platform independent template and finish your platform IIC driver.
Add the /src directory, the interface driver for your platform, and your own drivers to your project, if you want to use the default example drivers, add the /example directory to your project.
You can refer to the examples in the /example directory to complete your own driver. If you want to use the default programming examples, here's how to use them.
#include "driver_pcf8574_basic.h"
uint8_t res;
pcf8574_pin_level_t level;
/* basic init */
res = pcf8574_basic_init(PCF8574_ADDRESS_A000);
if (res != 0)
{
return 1;
}
...
/* read pin */
res = pcf8574_basic_read(PCF8574_PIN_0, (pcf8574_pin_level_t *)&level);
if (res != 0)
{
(void)pcf8574_basic_deinit();
return 1;
}
/* write pin */
res = pcf8574_basic_write(PCF8574_PIN_0, PCF8574_PIN_LEVEL_HIGH);
if (res != 0)
{
(void)pcf8574_basic_deinit();
return 1;
}
...
(void)pcf8574_basic_deinit();
return 0;Online documents: https://www.libdriver.com/docs/pcf8574/index.html.
Offline documents: /doc/html/index.html.
Please refer to CONTRIBUTING.md.
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