PCA9535 GPIO Expander

PCA9535 is a GPIO expander with 16 IO lines which has I2C bus interface. It provides additional IOs for I2C bus master such as SBC or MCU that can be used to read push button or sensor, to control LED, etc. PCA9555 is identical to PCA9535 except the presence of internal pull-up resistor which increases power consumption when the IOs are low. PCA9535C is another variation of PCA9535 with open drain outputs. Its operating supply voltage range is 2.3V to 5.5V. There are 3 hardware pins which allow to use 8 different I2C bus addresses, from 0x20 to 0x27.

• Setup
• C++ Example
• Using Device Overlay

ADS1115 ADC

ADS1115 is a precision, low power, 16 bit 860 SPS I2C analog to digital converter (ADC). It has internal reference, oscillator, and programmable comparator. ADS1115 modules are readily available at online markets like AliExpress and Adafruit

Figure 1. ADS1115 Adafruit module
( learn.adafruit.com/adafruit-4-channel-adc-breakouts/downloads).

DS1307 Real-time Clock

Using DS1307 Real-time clock is discussed. A module in AliExpress costs only about $1. It even consists of a 32k EEPROM called AT24C32.

Figure. Setup.

Accelerometer LIS3DSH

LIS3DSH is an 3-axis MEMS accelerometer made by STMicroelectronics. Its full scale range is selectable from ±2g to ±16g. The size is small and it is only 3mm x 3mm. Either SPI or I²C can be used to interface with it. Supply voltage is from 1.71 V to 3.6 V. In this article, testing and evaluation of STEVAL-MKI134V1 adapter board is discussed.

Figure. STEVAL-MKI134V1 - LIS3DSH adapter board for standard DIL24 socket.