Tagged Questions

4
votes
2answers
86 views

How to deal with multiple pull-up resistors on modules

I was thinking about doing a modules for a development board I did a few days ago that will include spi/i2c interfaces. The problem is that I didn't included pull-up resistors in the MCU pins in the ...
1
vote
1answer
54 views

TCA9555 Analog I/O

I understand that the TCA955 is an I/O extender that communicates via a I2C bus. What I can't figure out is whether this chip will take analog inputs as well as digital inputs. I'm trying to add more ...
2
votes
3answers
198 views

Generation of text on composite video

I'm building a homebrew computer. I want some way to get video out, preferably along the lines of 80x25 text. I'm not interested in framebuffer graphics. Does such a thing exist as a single-chip text ...
2
votes
2answers
117 views

I2C: Is a repeated start between different slave addresses legal?

I'm writing I²C code for an application where I have only one master, but several slaves. In all the datasheets I've read (not only for this project), the repeated start condition is only used to ...
1
vote
3answers
694 views

Starting with I2C on PIC18s

For a project I'd like three PICs (two slaves PIC18F4620, one master PIC18F46K22) to communicate over the I2C bus. Later on, more slaves may be added (like EEPROM, SRAM, ...). I'm writing the code for ...
1
vote
1answer
230 views

How to shift cursor of a ST7032i based LCD?

I am using a MIDAS MCCOG21605B6W, I2C interfaced, COG type LCD. I am also using a PIC16F616 microcontroller to interface it and I am bit-banging the I2C protocol. I can initialize the LCD, write to ...
2
votes
3answers
232 views

Can I use I2C bus or GPIOs as I2C to connect I2C devices?

This question is regarding use of I2C Bus/GPIOs as I2C. My application processor has three I2C controllers. Is it preferable to connect all I2C devices (obviously we can not connect more than 128 ...
0
votes
1answer
81 views

Keep SPI/TWI master active?

I'm designing a data recorder application which uses an 8-bit AVR microcontroller. It uses the TWI and SPI interfaces with the microcontroller being the master. There is one SPI device, a microSD ...
1
vote
1answer
444 views

Multiple 4-Digit 7 Segment Displays with Arduino

I have 3, 4-Digit 7-Segment Displays from Adafruit, and the included docs/ libraries say I should connect the display to pins A4 & A5. However, I have three of the displays, so I am looking for a ...
-2
votes
1answer
313 views

Interface microcontroller as i2c slave

How do I configure an I2C enabled microcontroller (NXP P89LPC9321) as a slave for the I2C enabled master? I have done some study on I2C interface. Please throw some light on this, preferably some ...
2
votes
1answer
427 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 ...
1
vote
1answer
506 views

Soft i2c with Sensirion SHT21 sensors on Arduino Mega

I have tried checking with an oscilloscope on the analogue pins when the sensor is plugged in and I don't seem to get anything as I normally would. The hardware i2c channel works just fine on the ...
3
votes
1answer
1k views

Picotux alternatives available?

I wanted to use a tiny Linux computer to read data from I²C bus. I knew there was Picotux, and I was thingking about buying one. But the website is down, so I guess there's no Picotux anymore. :( ...
3
votes
2answers
251 views

What kind of issues might I face when moving from 400 kHz I2C to 1 MHz I2C?

I'm thinking of migrating from an I2C bus at 400 kHz to one running at nearly 1 MHz. I am using 1.2k pull-ups at the moment and on the clock and data lines, I get a rise time of 383ns average when ...
5
votes
5answers
466 views

Is it possible to use 400 kHz I2C buses with a 32 kHz slave?

I am going to use a 400 kHz I2C bus, but I want to talk to a slave MCU, a PIC16F690 (datasheet), running at 32 kHz. Is it possible to do this? I think so, because the master does the clocking, but are ...