Comments on: Guide for TCA9548A I2C Multiplexer: ESP32, ESP8266, Arduino

By: Ruben Oliva Ramos

Ruben Oliva Ramos — Wed, 24 Sep 2025 19:51:58 +0000

Hi
I fixed the problem the module was damage

Thanks

By: Sara Santos

Sara Santos — Wed, 24 Sep 2025 19:27:58 +0000

In reply to Ruben Oliva Ramos.

Hi.
Can you share what is exactly the problem?
Regards,
Sara

By: Ruben Oliva Ramos

Ruben Oliva Ramos — Sat, 20 Sep 2025 23:57:59 +0000

Hi
I have already done this, the same problem
Question Do I need to connect the four sensors at the same time, I only have one connected.

By: Sara Santos

Sara Santos — Sat, 20 Sep 2025 18:39:22 +0000

In reply to Ruben.

Hi.
Downgrade your ESP32 boards installation to version 3.2.0.
Tools > Boards > Boards Manager > ESP32 and downgrade.
See if that fixes the issue.
Regards,
Sara

By: Ruben

Ruben — Sat, 20 Sep 2025 01:55:14 +0000

I have a question:

It apperars this in the serial monitor

E (8) i2c.master: I2C hardware NACK detected
E (9) i2c.master: I2C transaction unexpected nack detected
E (9) i2c.master: s_i2c_synchronous_transaction(945): I2C transaction failed
E (13) i2c.master: i2c_master_multi_buffer_transmit(1214): I2C transaction failed
Could not find a valid BME280 sensor on bus 2, check wiring!

By: Sara Santos

Sara Santos — Mon, 11 Aug 2025 11:23:25 +0000

In reply to K Suryanarayana.

Hi.
I’m sorry. But I’m not sure if I understood your question.
If you have a breakout board, and not just the chip, it usually already includes the pull-up resistors and you can use it directly.
Regards,
Sara

By: K Suryanarayana

K Suryanarayana — Sat, 09 Aug 2025 06:37:40 +0000

In reply to Sara Santos. Hii, I have a PCA9548A 8-channel mux. The document shows every I2C connection, used pull-up resistors, or can I use it directly?

By: Babak

Babak — Tue, 07 May 2024 20:55:27 +0000

thank you. Your website helped me a lot.

By: Jefferso Leles

Jefferso Leles — Fri, 16 Feb 2024 20:35:28 +0000

Hello, excellent tutorial, rich material of information!

I would like to know if I can read the data from 3 ADXL345 accelerometer sensors with the TCA9548A on the ESP32, and what would it look like?

Grateful!

By: Jacques

Jacques — Mon, 05 Feb 2024 11:05:50 +0000

Hello Sara,

I used the exact same code as you posted, with 4 bme280 and a PCA9546, which should work the same (isnt it ?).
It works for the first loop, but give nonsense and reboots at the second.
I posted a question on the forum.

below is the main loop

Thanks for any help

Jacques

void loop() {
//Print values for sensors
printValues(bme0, 0);
printValues(bme1, 1);
printValues(bme2, 2);
printValues(bme3, 3);
delay(5000);
Serial.println(” end of loop”);
}

Here is the output :

Sensor number on bus0
Temperature = 22.21 *C
Pressure = 1022.59 hPa
Humidity = 52.52 %

Sensor number on bus1
Temperature = 21.92 *C
Pressure = 1021.75 hPa
Humidity = 50.33 %

Sensor number on bus2
Temperature = 21.68 *C
Pressure = 1020.94 hPa
Humidity = 53.21 %

Sensor number on bus3
Temperature = 22.04 *C
Pressure = 1021.31 hPa
Humidity = 51.59 %

end of loop
Sensor number on bus0
Temperature = 183.15 *C
Pressure = -133.56 hPa
Humidity = 100.00 %

————— CUT HERE FOR EXCEPTION DECODER —————

Exception (3):
epc1=0x4010084d epc2=0x00000000 epc3=0x00000000 excvaddr=0x4003bff9 depc=0x00000000

stack>>>

ctx: cont
sp: 3ffffdb0 end: 3fffffd0 offset: 0150
3fffff00: 00000568 000000ad 3ffe85e4 40100906
3fffff10: 40202cd4 3ffe889b 3ffee860 3ffee8e0
3fffff20: 3fffdad0 00000020 3ffef7c4 40100c54
3fffff30: 40202cd4 00000000 3fffff50 402015c2
3fffff40: 3fffdad0 00000000 00000054 402012a4
3fffff50: 3ffef7c4 00000000 00000000 00000000
3fffff60: 00000000 00000000 00000060 000e4ef1
3fffff70: 00000000 67546ce2 92440032 0bd0d678
3fffff80: ffdb1ad6 300cfff9 1388d120 0149004b
3fffff90: 01970000 001e0032 00000000 000000ed
3fffffa0: 000000a0 00000000 3ffee8b4 3ffee8e0
3fffffb0: 00000000 00000000 3ffee8b4 40203670
3fffffc0: feefeffe feefeffe 3fffdab0 40101001
<<

————— CUT HERE FOR EXCEPTION DECODER —————