All Questions
21 questions
0
votes
1
answer
81
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Why are GPIO Expander Registers Being Rewritten?
I'm using an LPC1768 microcontroller (mbed) and 4 GPIO expanders (MCP23017). I am trying to write to the expanders to enable the pull up resistors and some other functions, but am getting strange ...
0
votes
1
answer
131
views
Two PCF8574 detected but not the third PCF8574
I'll be using an Arduino Nano 33 IoT together with three PCF8574 IO expander boards. I've managed to connect two PCF8574s together and communicate to each of them individually at different address ...
0
votes
1
answer
165
views
Issues with I2C from MCP23017on Arduino
I am trying to use the MCP23017 expander chip with a Metro Mini by Adafruit (pinout below) and I can't get the microcontroller to connect reliably via I2C.
update
I connected the RESET pin to 5V and ...
- 321
5
votes
1
answer
609
views
Why does read from I2C GPIO Expander MCP23017 requires NACK
I'm using the MCP23017 16-bit I2C GPIO Expander in combination with the microcontroller PIC18F47J53. Both products are from Microchip.
Datasheet MCP23017
Datasheet PIC18F47J53
I use MCC (MPLab Code ...
- 147
0
votes
4
answers
155
views
I2C Strange goings on
I am using a Teensy 4.0 and an MCP23016 Port Expander (only I2C device) on my PCB.
I have 4k7 pullups to 3V3 on SDA & SCK.
SCK track is 77.9 mm long, 0.254 wide.
SDA 64.3 mm long, 0.254 wide.
I ...
0
votes
0
answers
320
views
PCF8574 and OLED SSD1306 I2C conflict
I have a ESP12 module which is connected to multiple I2C devices such as an 24C08 EEPROM, DS1307 RTC and a PC8574 expander.
Everything works fine until I decided to add an OLED module to this setup. ...
- 17
3
votes
5
answers
5k
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UART expander (5 ports to 11 ports)
I have a board that I would like to design and there are 11 devices that can only be spoken to via UART. I am restricted to a Microchip uC chip product range and I have found one with 5 UART ports. I ...
- 389
1
vote
1
answer
226
views
Pull up/down a pin on a PCA9536 does not register?
Quite a obscure question here, concerning a very specific I2C expander IC, however I believe that this example can be replicated with most expander bus ICs.
I am using a PCA9536 to switch the 4 pins ...
- 13
0
votes
2
answers
3k
views
Multiple analog inputs on A0 pin (ESP nodemcu) with PCF8574
I am trying to read out several analog values on one analog input on the nodemcu.
As sensors I am using two potentiometers which are connected to GND via a PCF8574 8-bit I/O expander.
With the code ...
- 1
0
votes
1
answer
848
views
Will continuously polling I2C port expander damage it or reduce its life?
I am using I2C port expanders namely TCA9554A and TCA6424A in my project. I have two options to read the inputs - (a) wait for interrupt and read (b) continuously keep polling the chip for any input ...
- 8,501
0
votes
1
answer
789
views
Will MCP23017-E/SP be compatible with an ATtiny85? ATmega328P?
I mainly want to also be able to use the same I/O expanders with ATTiny85 projects since those chips have limited pins.
I will be doing the main prototyping on an ...
user11995
3
votes
1
answer
908
views
How to read SAA1064 7-segment values
I have a central heating system that displays it's info and error codes on 4 7-segment displays. These displays are driven by a SAA1064, like so:
This SAA1064 (datasheet here) receives it's ...
- 329
1
vote
0
answers
305
views
MCP23017s and arduino problems
I'm not native English speaker, so forgive me my bads.
Ok. Here's the deal.
In my Arduino UNO I need more outputs and inputs. I bought 3 MCP23017s. One of them for receive states from 8 ...
- 11
3
votes
3
answers
1k
views
Do you always need a GPIO expansion chip when using i2c?
SUMMARY:
I'm trying to learn the basics of understanding how to wire up a simple circuit using the i2c. I'm wanting to build just a simple project involving an LED and a push button with my raspberry ...
- 1,049
0
votes
1
answer
525
views
MCP23017 in series
I have a hand full of MCP23017 (16 bit multiplexers/ I/O Expander) but I can only get 8 IC on the bus due to the limit of address but I need 200 pins (about 13 ICs) for a 8*8*8 RGB cube
and was ...
3
votes
3
answers
513
views
Increase GPIO outputs
I'm working on a project in which I need 32 outputs from an MCU that only has 8 free outputs.
To accomplish my goal I have the following requirements:
I must be able to toggle more than one output ...
- 1,012
5
votes
1
answer
3k
views
i2c over gpio - level shifter
I'm quite new to this. I have just basic background in electronics. So I would appreciate an advice from someone more experienced.
I would like to connect an i2c display to my tp-link wr703n (ar9331) ...
- 145
1
vote
2
answers
2k
views
Problem with transmitting data from PIC18F45K20 (C18) to MCP23017
I am currently testing the MCP23017 (slave device) 16 bit I/O Expander using a PIC18F45K20 with the C18 compiler to transmit data to the MCP23017. The address pins (A0, A1 and A2) of the MCP23017 are ...
- 61
1
vote
1
answer
919
views
How do I connect non-I2C devices to an I2C bus?
I'm quite new to electronics and just trying to do my first Raspberry Pi based system: one diode, one pressure sensor and LCD 1602 with keypad shield (the one for an Arduino board). The way I'd like ...
- 113
0
votes
2
answers
759
views
Multiplex two I2C ICs into four 7 Segment displays
I currently have two PCF8574AN I2C 8-bit IO expander ICs. Is there a way I could have two seven segments be driven off one IC (So i could run four seven segments displays off the two ICs that I have). ...
- 313
3
votes
1
answer
3k
views
Problem writing to MCP23017 I/O Expander registers (i2c)
I am creating a basic cable tester device and using I2C to interface with two MCP23017 I/O expander chips.
In my code each MCP23017 slave has its own address and I can communicate with both of them ...
- 133