Module - TCA9548A - I2C multiplexer

Hardware

Informatie (ENG)

Description

The TCA9548A device has eight bidirectional translating switches that can be controlled through the I²C bus. The SCL/SDA upstream pair fans out to eight downstream pairs, or channels. Any individual SCn/SDn channel or combination of channels can be selected, determined by the contents of the programmable control register. These downstream channels can be used to resolve I²C slave address conflicts. For example, if eight identical digital temperature sensors are needed in the application, one sensor can be connected at each channel: 0-7.

The system master can reset the TCA9548A in the event of a time-out or other improper operation by asserting a low in the RESET input. Similarly, the power-on reset deselects all channels and initializes the I²C/SMBus state machine. Asserting RESET causes the same reset and initialization to occur without powering down the part. This allows recovery should one of the downstream I²C buses get stuck in a low state.

The pass gates of the switches are constructed so that the VCC pin can be used to limit the maximum high voltage, which is passed by the TCA9548A. Limiting the maximum high voltage allows the use of different bus voltages on each pair, so that 1.8-V, 2.5-V or 3.3-V parts can communicate with 5-V parts, without any additional protection. External pullup resistors pull the bus up to the desired voltage level for each channel. All I/O pins are 5-V tolerant.

Features

1-to-8 Bidirectional Translating Switches
I²C Bus and SMBus Compatible
Active-Low Reset Input
Three Address Pins, Allowing up to Eight TCA9548A Devices on the I²C Bus
Channel Selection Through an I²C Bus, In Any Combination
Power Up With All Switch Channels Deselected
Low R_ON Switches
Allows Voltage-Level Translation Between 1.8-V, 2.5-V, 3.3-V, and 5-V Buses
No Glitch on Power Up
Supports Hot Insertion
Low Standby Current
Operating Power-Supply Voltage Range of
1.65 V to 5.5 V
5-V Tolerant Inputs
0- to 400-kHz Clock Frequency
Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II
ESD Protection Exceeds JESD 22
- ±2000-V Human-Body Model (A114-A)
- 200-V Machine Model (A115-A)
- ±1000-V Charged-Device Model (C101)

Applicaties

Servers
Routers (Telecom Switching Equipment)
Factory Automation
Products With I²C Slave Address Conflicts (Such as Multiple, Identical Temperature Sensors)

Pinout

Simplified Application Diagram

Adres van de chip/module instellen kan met de A0/A1/A2 pins:

Dit geeft de mogelijkheid om 8×8 = 64 I2C modules aan te sluiten met het zelfde I2C adres:

Arduino

Sluit de module aan volgens onderstaand schema.

Script

Je hebt voor het aansturen van deze chip/module geen speciale bibliotheek nodig, aansturen via de arduino code gaat als volgt:

#include <Wire.h>

#define TCAADDR 0x70

void tcaselect(uint8_t i) {
  if (i > 7) return;
  Wire.beginTransmission(TCAADDR);
  Wire.write(1 << i);
  Wire.endTransmission(); 
}

void setup(){
  Wire.begin();
}

void loop() {    
  tcaselect(0); // Selecteer kanaal 0
  // Doe I2C dingen.

  delay(100);  

  tcaselect(1); // Selecteer kanaal 1
  // Doe I2C dingen.

  delay(1000);
}

#include <Wire.h>

#define TCAADDR 0x70

void tcaselect(uint8_t i) {

if (i > 7) return;

Wire.beginTransmission(TCAADDR);

Wire.write(1 << i);

Wire.endTransmission();

}

void setup(){

Wire.begin();

}

void loop() {

tcaselect(0); // Selecteer kanaal 0

// Doe I2C dingen.

delay(100);

tcaselect(1); // Selecteer kanaal 1

// Doe I2C dingen.

delay(1000);

}

Voorbeeld voor het uitlezen van 2 BME280 sensoren:

#include <BME280I2C.h>
#include <Wire.h>

#define TCAADDR 0x70
#define SERIAL_BAUD 9600

BME280I2C bme;    // Default : forced mode, standby time = 1000 ms
                  // Oversampling = pressure ×1, temperature ×1, humidity ×1, filter off,

float pres, temp, hum;

void tcaselect(uint8_t i) {
  if (i > 7) return;
  Wire.beginTransmission(TCAADDR);
  Wire.write(1 << i);
  Wire.endTransmission(); 
}

void setup(){
  Serial.begin(SERIAL_BAUD);
  while(!Serial) {} // Wait
  Wire.begin();
  bme.begin();
}

void loop() {    
   BME280::TempUnit tempUnit(BME280::TempUnit_Celsius);
   BME280::PresUnit presUnit(BME280::PresUnit_Pa);
   
   tcaselect(0);
   bme.read(pres, temp, hum, tempUnit, presUnit);
   
   Serial.print("\tTemp1: "); Serial.print(temp); Serial.print("C");
   Serial.print("\tHum1: "); Serial.print(hum); Serial.print("% RH");
   Serial.print("\tPres1: "); Serial.print(pres); Serial.println(" Pa");
   
   delay(100);
   
   tcaselect(1);
   bme.read(pres, temp, hum, tempUnit, presUnit);
   Serial.print("\tTemp2: "); Serial.print(temp); Serial.print("C");
   Serial.print("\tHum2: "); Serial.print(hum); Serial.print("% RH");
   Serial.print("\tPres2: "); Serial.print(pres); Serial.println(" Pa");
   
   delay(1000);
}

#include <BME280I2C.h>

#include <Wire.h>

#define TCAADDR 0x70

#define SERIAL_BAUD 9600

BME280I2C bme; // Default : forced mode, standby time = 1000 ms

// Oversampling = pressure ×1, temperature ×1, humidity ×1, filter off,

float pres, temp, hum;

void tcaselect(uint8_t i) {

if (i > 7) return;

Wire.beginTransmission(TCAADDR);

Wire.write(1 << i);

Wire.endTransmission();

}

void setup(){

Serial.begin(SERIAL_BAUD);

while(!Serial) {} // Wait

Wire.begin();

bme.begin();

}

void loop() {

BME280::TempUnit tempUnit(BME280::TempUnit_Celsius);

BME280::PresUnit presUnit(BME280::PresUnit_Pa);

tcaselect(0);

bme.read(pres, temp, hum, tempUnit, presUnit);

Serial.print("\tTemp1: "); Serial.print(temp); Serial.print("C");

Serial.print("\tHum1: "); Serial.print(hum); Serial.print("% RH");

Serial.print("\tPres1: "); Serial.print(pres); Serial.println(" Pa");

delay(100);

tcaselect(1);

bme.read(pres, temp, hum, tempUnit, presUnit);

Serial.print("\tTemp2: "); Serial.print(temp); Serial.print("C");

Serial.print("\tHum2: "); Serial.print(hum); Serial.print("% RH");

Serial.print("\tPres2: "); Serial.print(pres); Serial.println(" Pa");

delay(1000);

}

Console output:

	Temp1: 14.31C	Hum1: 34.52% RH	Pres1: 99211.87 Pa
	Temp2: 17.60C	Hum2: 58.71% RH	Pres2: 100469.41 Pa
	Temp1: 14.31C	Hum1: 34.52% RH	Pres1: 99215.34 Pa
	Temp2: 17.60C	Hum2: 58.75% RH	Pres2: 100472.06 Pa
	Temp1: 14.32C	Hum1: 34.51% RH	Pres1: 99216.18 Pa
	Temp2: 17.61C	Hum2: 58.73% RH	Pres2: 100480.87 Pa
	Temp1: 14.31C	Hum1: 34.52% RH	Pres1: 99217.97 Pa
	Temp2: 17.61C	Hum2: 58.73% RH	Pres2: 100476.44 Pa
	Temp1: 14.31C	Hum1: 34.53% RH	Pres1: 99207.46 Pa
	Temp2: 17.61C	Hum2: 58.72% RH	Pres2: 100476.44 Pa
	Temp1: 14.32C	Hum1: 34.53% RH	Pres1: 99214.39 Pa
	Temp2: 17.61C	Hum2: 58.73% RH	Pres2: 100476.44 Pa
	Temp1: 14.32C	Hum1: 34.53% RH	Pres1: 99211.77 Pa
	Temp2: 17.61C	Hum2: 58.73% RH	Pres2: 100479.08 Pa
	Temp1: 14.32C	Hum1: 34.54% RH	Pres1: 99217.02 Pa
	Temp2: 17.62C	Hum2: 58.74% RH	Pres2: 100474.64 Pa

Temp1: 14.31C Hum1: 34.52% RH Pres1: 99211.87 Pa

Temp2: 17.60C Hum2: 58.71% RH Pres2: 100469.41 Pa

Temp1: 14.31C Hum1: 34.52% RH Pres1: 99215.34 Pa

Temp2: 17.60C Hum2: 58.75% RH Pres2: 100472.06 Pa

Temp1: 14.32C Hum1: 34.51% RH Pres1: 99216.18 Pa

Temp2: 17.61C Hum2: 58.73% RH Pres2: 100480.87 Pa

Temp1: 14.31C Hum1: 34.52% RH Pres1: 99217.97 Pa

Temp2: 17.61C Hum2: 58.73% RH Pres2: 100476.44 Pa

Temp1: 14.31C Hum1: 34.53% RH Pres1: 99207.46 Pa

Temp2: 17.61C Hum2: 58.72% RH Pres2: 100476.44 Pa

Temp1: 14.32C Hum1: 34.53% RH Pres1: 99214.39 Pa

Temp2: 17.61C Hum2: 58.73% RH Pres2: 100476.44 Pa

Temp1: 14.32C Hum1: 34.53% RH Pres1: 99211.77 Pa

Temp2: 17.61C Hum2: 58.73% RH Pres2: 100479.08 Pa

Temp1: 14.32C Hum1: 34.54% RH Pres1: 99217.02 Pa

Temp2: 17.62C Hum2: 58.74% RH Pres2: 100474.64 Pa

Raspberry Pi

Sluit de module aan volgens onderstaand schema.

TCA9548A module:	RPI functie:	RPI pin:
VIN	VCC 3.3V	1
GND	GND	6
SDA	SDA	3
SCL	SCL	5
A0	GND	6
A1	GND	6
A2	GND	6

Standaard heeft deze module I2C adres 0x70:

Script

Onderstaand script schakelt naar I2C kanaal 3

#!/usr/bin/python
# TCA9548A I2C multiplexer
# I2C Address: 70 through 77
# Channel: 0 - 7

import smbus

# class for the I2C switch
class I2C_SW(object):
  # init
  def __init__(self,name,address,bus_nr):
    self.name=name
    self.address=address
    self.bus_nr=bus_nr
    self.bus=smbus.SMBus(bus_nr)

  # Change to i2c channel 0..7
  def chn(self,channel):
    self.bus.write_byte(self.address,2**channel)

  # block all channels read only the main I2c (on which is the address SW)
  def _rst(self):
    self.bus.write_byte(self.address,0)
    print self.name,' ','Switch reset'

  # read all 8 channels
  def _all(self):
    self.bus.write_byte(self.address,0Xff)
    print self.name,' ','Switch read all lines'

# define the usual sensor 0X70 bus 1
SW=I2C_SW('I2C switch 0',0X70, 1)

# SW._all()
# SW._rst()
# Selecteer kanaal nummer (0-7)
# controleer met i2cdetect y -1 (if bus_nr=1)

SW.chn(3)

#!/usr/bin/python

# TCA9548A I2C multiplexer

# I2C Address: 70 through 77

# Channel: 0 - 7

import smbus

# class for the I2C switch

class I2C_SW(object):

# init

def __init__(self,name,address,bus_nr):

self.name=name

self.address=address

self.bus_nr=bus_nr

self.bus=smbus.SMBus(bus_nr)

# Change to i2c channel 0..7

def chn(self,channel):

self.bus.write_byte(self.address,2**channel)

# block all channels read only the main I2c (on which is the address SW)

def _rst(self):

self.bus.write_byte(self.address,0)

print self.name,' ','Switch reset'

# read all 8 channels

def _all(self):

self.bus.write_byte(self.address,0Xff)

print self.name,' ','Switch read all lines'

# define the usual sensor 0X70 bus 1

SW=I2C_SW('I2C switch 0',0X70, 1)

# SW._all()

# SW._rst()

# Selecteer kanaal nummer (0-7)

# controleer met i2cdetect y -1 (if bus_nr=1)

SW.chn(3)

Schema

Teardown

GEEN GEGEVENS

Datasheet

Fritzing

TCA9548A I2C multiplexer.fzpz 16,34 kb

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