Achieve incredible success in analog multiplexing with CD74HC4067 and STM32L4R9AI
The ultimate analog switching solution
Published Sep 23, 2023
Click board™
Analog MUX Click
Dev. board
Discovery kit with STM32L4R9AI MCU
Compiler
NECTO Studio
MCU
STM32L4R9AI
Achieve precise control over analog signals in complex systems with our 16-channel input switching solution optimized for high-performance applications in various industries
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Hardware Overview
How does it work?
Analog MUX Click is based on the CD74HC4067, a high-speed CMOS logic 16-channel analog multiplexer/demultiplexer from Texas Instruments. It supports 3.3V and 5V power supplies, as well as rail-to-rail operation, allowing it to be used in various applications. Four control pins switch one of sixteen inputs to a single output. Control pins labeled as S0, S1, S2, and S3 are routed to the mikroBUS™ and can be operated by both 3.3V and 5V MCUs. These pins are routed to the RST, PWM, INT, and CS pins of the mikroBUS™, respectively, while the common output pin from the multiplexer is routed to the AN pin on the mikroBUS™. The CD74HC4067 IC is digitally controlled analog switch that utilize silicon-gate CMOS technology to achieve operating speeds similar to LSTTL, with the low power
consumption of standard CMOS integrated circuits. The mentioned analog multiplexer/demultiplexer control analog voltages that may vary across the voltage supply range. The ultra-low leakage current ensures that there is no signal interference from the inputs that are not selected by the S0, S1, S2, and S3 pins. A low crosstalk also ensures that the signal on one channel remains clean of interferences caused by other channels. To prevent any two inputs to be switched at the output at the same time, a break-before-make switching action is utilized. This ensures a reliable operation of the IC and the Click board™ itself. Analog MUX click is bidirectional switch as well, thus allowing any analog input to be used as an output and vice-versa. The switches have low “on” resistance and low “off” leakages.
All of the input channels can be easily connected to the two 9 pole spring action block terminals, without having to use any additional tools, such as screwdrivers. More information about the CD74HC4067 can be found in the attached datasheet. However, the Click board™ comes equipped with a library that contains easy to use functions and a usage example that may be used as a reference for the development. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.
Features overview
Development board
Discovery kit with STM32L4R9AI MCU is a complete demonstration and development platform for the STMicroelectronics Arm® Cortex®-M4 core-based STM32L4R9AI microcontroller. Leveraging the innovative ultra-low-power oriented features, 640 Kbytes of embedded RAM, graphics performance (Chrom-ART Accelerator™), and DSISM controller offered by the STM32L4R9AI, the 32L4R9IDISCOVERY kit enables users to easily prototype applications with state-of-the-art energy efficiency, as well as providing stunning audio and graphics rendering with direct support for an AMOLED DSI round display. For even more user friendliness, the on-board ST-LINK/V2-1 debugger provides out-of-the-box programming and
debugging capabilities. The STM32L4R9AI microcontroller features four I2Cs, five USARTs, one ULP UART, three SPIs, two SAIs, one SDIO, one USB 2.0 full-speed OTG, two CANs, one FMC parallel synchronous interface, one 12 bit ADC, one 12-bit DAC, two ULP analog comparators, two op-amps, one two data-lane DSI display, one digital filter for sigma-delta modulation and SWP interface, two Octo-SPI interfaces, an 8- to 14-bit camera interface, one touch-sensing controller interface, JTAG, and SWD debugging support. This Discovery board offers everything users need to get started quickly and develop applications easily. The hardware features on the board help to evaluate the following peripherals: USB OTG FS, microSD™
card, 8-bit camera interface, 16-Mbit PSRAM, PMOD, and STMod+ connectors, IDD measurement, full-duplex I2S with an audio codec and stereo headset jack including an analog microphone, DFSDM with a pair of MEMS digital microphones on board, 512-Mbit Octo-SPI Flash memory device, I2C extension connector, 1.2" AMOLED display using a one data-lane DSI interface with a capacitive touch panel. The ARDUINO® compatible connectors expand the functionality with a wide choice of specialized shields. The integrated ST-LINK/V2-1 provides an embedded in-circuit debugger and programmer for the STM32 MCU.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
2048
Silicon Vendor
STMicroelectronics
Pin count
169
RAM (Bytes)
655360
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Discovery kit with STM32L4R9AI MCU as your development board.
Track your results in real time
Application Output
1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.
2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.
3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.
Software Support
Library Description
This library contains API for Analog MUX Click driver.
Key functions:
analogmux_get_voltage- Generic read voltage functionanalogmux_set_channel- This function sets the active channel on the MUX.
Open Source
Code example
The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.
/*!
* \file
* \brief AnalogMUX Click example
*
* # Description
* This example showcases how to initialize, configure and use the Analog MUX Click module.
* The Click switches one of the 16 inputs to output so the adc value of that input
* can be read on the COM (AN) pin. The RST, PWM, CS and INT are used as control output pins.
*
* The demo application is composed of two sections :
*
* ## Application Init
* This function initializes and configures the logger and Click modules.
*
* ## Application Task
* This function reads ADC value and voltage from channel 0 (AN0) and shows the results
* on the USB UART every 2 seconds.
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "analogmux.h"
// ------------------------------------------------------------------ VARIABLES
static analogmux_t analogmux;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
analogmux_cfg_t cfg;
/**
* Logger initialization.
* Default baud rate: 115200
* Default log level: LOG_LEVEL_DEBUG
* @note If USB_UART_RX and USB_UART_TX
* are defined as HAL_PIN_NC, you will
* need to define them manually for log to work.
* See @b LOG_MAP_USB_UART macro definition for detailed explanation.
*/
LOG_MAP_USB_UART( log_cfg );
log_init( &logger, &log_cfg );
Delay_100ms( );
log_info( &logger, "---- Application Init ----" );
// Click initialization.
analogmux_cfg_setup( &cfg );
ANALOGMUX_MAP_MIKROBUS( cfg, MIKROBUS_1 );
analogmux_init( &analogmux, &cfg );
analogmux_set_channel( &analogmux, ANALOGMUX_CHANNEL_0 );
log_printf( &logger, " Channel 0 enabled\r\n" );
log_printf( &logger, " -------------------\r\n" );
}
void application_task ( void )
{
uint16_t tmp;
float val;
tmp = analogmux_generic_read( &analogmux );
log_printf( &logger, " ADC value : %u\r\n", tmp );
val = analogmux_generic_read_voltage( &analogmux );
log_printf( &logger, " Voltage: %.3f mV\r\n", val );
log_printf( &logger, " -------------------\r\n" );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
}
int main ( void )
{
/* Do not remove this line or clock might not be set correctly. */
#ifdef PREINIT_SUPPORTED
preinit();
#endif
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END
Additional Support
Resources
Category:Port expander
