Tagged Questions

1
vote
0answers
18 views

Adafruit SSD1306, I2C, ATmega1284p: OLED Display askew/misaligned

Another strange problem here. The setup: Adafruit SSD1306 OLED board connected to an ATMega1284p via I2C. Since I "upped" my 1284 to 8MHz (which I needed to to reliably talk to my temperature ...
1
vote
1answer
39 views

OneWire DS18B20 on mighty 1284p can't find my sensors, same sensors work w/ Duemilanove

I have uploaded the DS18x20 Temperature example sketch (unaltered, except I tried multiple pins for the I2C communication) to my proven Duemilanove and my ...
2
votes
1answer
60 views

should I use 2 SPI devices on Arduino UNO/PRO or 2 I2C devices?

I am using a microSD breakout board and the accelerometer ADXL345 https://www.sparkfun.com/products/9836. each one alone works perfectly fine, but once I put both (sharing pins 11,12,13, but with ...
0
votes
2answers
88 views

Strange I2C behavior: sometime it works, some time it doesn't

I am using Arduino Ethernet with PoE and Arduino Uno boards. In recent days I implemented a working I2C bus by using the Wire library and all it seemed almost to ...
1
vote
1answer
106 views

I2C with DS1307 hang after end of transmission

I've got a home brewed RTC with DS1307. I've put two pullup resistors on SDA and SCL lines, connected them to the Arduino 5 and 6 pin respectively. I've also provided a backup battery since I read ...
0
votes
2answers
155 views

I2C temp sensor and an Arduino wifi shield not working together

I am using an arduino wifi shield and a TMP102 with an arduino uno rev2. With boards older than rev3 you have to add a jumper from the 3.3V to the IOREF pin for the wifi shield, see here: ...
2
votes
2answers
179 views

Sync 12 Arduinos - I2C vs Serial

I've been given 12 arduinos (Mega) and 12 breakout boards (custom built. they pump up the output of the digital pins to 12v @120mA) to control around 300 LEDs. I'm using a pseudo PWM library to fade ...
2
votes
1answer
122 views

TLC59116F (i2c led driver) everything seems ok but LED doesn't work

I'm trying the LED driver TLC59116F with an arduino UNO R3. This IC is a i2c controllable LED driver with PWM and 16 outputs. The registers seem all loaded fine, here's a print of their contents: ...
1
vote
1answer
158 views

Multiple masters for i2c device

I have a DS1307 RTC chip that I want to interface with multiple masters. One, an ATMega chip, will only ever really need to pull time data from the chip and the other (probably just an ATTiny) will ...
4
votes
3answers
241 views

I2C wiring help

I have 64 i2c devices wired together. They all seem to work correctly until randomly between 30s-1m of sending signals, the bus will hang. Here is how I have it wired: It's currently wired as ...
5
votes
4answers
510 views

DS1307 power failure problem

the DS1307 has two power sources the main VCC source and the back up battery, which must feed the DS1307 when the power goes down and keep timing and here my problem, I am facing a problem with the ...
0
votes
2answers
344 views

How to test an atmega (arduino) i2c network

First of all sorry for my bad English and for this "theoretical" question on how is the best way to do things. I'm just out from university and no-one ever told me how problems can be resolved in a ...
1
vote
1answer
345 views

communication between 2 arduino crash when external power supply is plugged

i have one arduino mega that communicates with one arduino leonardo. the leonardo controls some motors (mega tell to the leonardo how many step to do... leonardo is a coprocessor for the motor in ...
1
vote
4answers
1k views

ATTiny25/45/85 as I2C master AND slave

I'm still trying to wrap my head around I2C as well as the ATTiny. I've found plenty of tutorials on how to use the tiny as an I2C slave as well as master, but is it possible to use it as both at the ...
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 ...
3
votes
3answers
2k views

multiple arduino communication (1 master, n slaves)

I would like to develop a master/slave network that consists of: 1 Arduino master that reads sensors and generates velocity ramp profiles based on the sensor signals and then sends those ramps to ...
2
votes
1answer
437 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 ...
2
votes
2answers
267 views

Arduino to CPLD to toggle an LEDs using I2C

I have a a CPLD (Lattice MachXO2) that echos a signal from an Arduino to turn on an LED. Arduino: ...
0
votes
2answers
932 views

LCD Programming with Arduino

I'm trying to get my LCD to display "Voltage= (variable)". I have it programmed to write the text and I have a pot wired to my arduino and I'm trying to get a voltage number to come after the equals ...
2
votes
1answer
2k views

How to make Arduino do High Speed I2C

I wired up two MCP4725 DAC's to my Arduino and wrote a little demo sketch to test functionality. The sketch draws a Lissajous curve on my oscilloscope. The output frequency is a bit disappointing ...
1
vote
1answer
515 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 ...
1
vote
1answer
3k views

How to connect multiple i2c-interface devices into a single pin A4 (SDA) and A5 (SCL) on Arduino?

I want to add a real time clock module into my little project. I want to display both time and date on my existing i2c 2x16 LCD module. Both i2c-interface real time clock module and 2x16 LCD module ...
2
votes
2answers
518 views

DS1307 RTC Debug

I'm having trouble with getting the DS1307 RTC to work. I'm talking to it via an Arduino, and I'm just trying to get an example sketch to work. I've tried two different libraries - one from Ladyada, ...
3
votes
1answer
930 views

Data from BMA180 accelerometer into arduino is sporadic

I've been trying to get a BMA180 (I'm on my second one already) to send a continuous stream of accel data via a serial port (eventually bluetooth but that's a problem for a different day). I've looked ...
1
vote
1answer
860 views

BMP085 and Humidity and Temperature Sensor with arduino

I am doing a project that requires me to use a BMP085 (with breakout) and a humidity/temperature sensor (with Breakout). I am trying to attach both of these to the arduino uno through two analog ...
2
votes
2answers
1k views

What is the speed of I2C for AVR communication?

I'm doing a project where I'll have a lot of slave ATtiny's and one master controller (either an Arduino/ATMega or an mbed). I assume the ATtiny with it's low clock speed of 10MHz will be my ...
2
votes
1answer
1k views

How do I read I2C memory with an Arduino?

I have HH100D humidity sensor. It outputs a frequency signal, which I know how to handle. However, it also has a small EEPROM with calibration values that is available via I2C. Those values are ...
6
votes
2answers
3k views

How do I get an Arduino (5 V) and MPR121 (3.3 V) to talk?

I have the Sparkfun MPR121 I2C Capacitive touch sensor breakout board I have read that it uses 3.3 V, I know that I can't just connect up the 3.3 V power supply output from the Arduino as the ...
22
votes
4answers
3k views

\$I^2C\$ 3.3 to 5.0 V conversion

I'm trying to interface a 3.3V \$I^2C\$ device to a 5V Arduino. I don't have any problem with SCL line. I can use a simple voltage divider but I have an issue with the SDA line as this is ...
7
votes
5answers
2k views

Implementing I2C to analog

How can I implement (or maybe there is an IC that already does that) a board whose input would be I2C and output would be analog voltage (0V - 5V) ? Eventually I would like to connect a couple of ...