I²C (Inter-Integrated Circuit) is a multi-drop serial bus invented by Philips (now NXP) for communication between ICs on the same PCB, i.e. short distance.
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i2c automatic address assignment
I have asked the question at http://stackoverflow.com/questions/19396584/i2c-automatic-address-assign and someone offered to ask here in order to get better answers, so here it is:
History:
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3answers
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i2C : pull-up resistors “design pattern”, armored cable and connector?
I'm designing an arduino based board which will uses I2C port a lot. I want to be able to connect several slave devices, and/or connect several mother boards together (at least 4 would be great). The ...
3
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1answer
45 views
Which interface is better for my OLED displayer?
I have a 0.96 inch 128x64 Yellow-Blue oled display module like this: OLED module and i want to use of it. The Driver is SSD1306. When you see in the SSD1306's datasheet you know it support 8-bit ...
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0answers
34 views
How to “read” SSD LED display by sniffing it's i2c communications with master?
Firstly I apologise if this question is more of a Raspberry Pi/Linux question but I've scoured the Raspi/Linux stack exchange boards and googled until my fingers fell off so I'm trying here in the ...
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2answers
75 views
Signal buffer/converter/recorder
Is there an IC that will "record" a digital signal received (highs and lows) record or buffer that input, and finally send to another IC thru I2C interface.
The problem is that I have two different ...
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I2C extender: 82B715
Does anyone know or have experience with the noise level, that the following I2C extender permits, while still being able to operate correctly?
I2C extender 82B715
It's datasheet mentions nothing.
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3answers
123 views
Multiplexing I2C devices with MOSFETs
Ok, I understand similar questions have been asked in the past, please bear with me. Here is my problem, I have 2 I2C devices to be connected to a single I2C bus. They happen to be the same component ...
2
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3answers
112 views
selectable power voltage
I want to build a circuit that will output multiple voltages (one at a time) to supply an FPGA. The core volt will be constant voltage. I want to be able to supply different voltages for the FPGA ...
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2answers
86 views
Protecting 3.3V I2C lines
Raspberry Pi has 3.3V I2C bus without any protection against overvoltage. So, I want to add protection against an accidental 5V level on the bus. How to do it?
My two tries:
simulate this ...
3
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1answer
128 views
Can't get I2C to work on PIC32 (“skips” bytes/hangs)
I am working on a PIC32-MAXI-WEB development board from Olimex that I'd like to have communicating with an Invensense MPU-6050 6DOF accelerometer/gyro. By modifying an demo from Olimex I managed to ...
4
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1answer
70 views
I2C with only ground common
I'm playing with I2C on an AVR. I need the devices separated, and each device has its own battery. For the I2C I'm not clear if it is OK to have the pull up resistor within the source device, then ...
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3answers
130 views
I²C, SPI, CAN protocoles and OSI model
could you please refer me to a reference or explain me if I²C, and SPI ** are just **Physical layer protocols in OSI model (i know that this model is for communication and maybe not exactly for ...
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1answer
157 views
How to improve I2C RTC accuracy
I´m using a PCF 8583 I2C RTC for one of my projects (i´m not a professional, just an amateur). The clock delays about an hour per day, which I find unacceptable.
I´m using a 32768 Hz, 12.5 pf, 50 ...
5
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1answer
100 views
L3G4200D random spikes
I've searched this forum a bit in regards to the L3G4200D gyroscope, and haven't seen this problem mentioned, but I have seen others talk about it on other forums. I am seeing a strange large value in ...
2
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1answer
133 views
IC: I2C communications over a DC bus
I have been looking everywhere for a method to use i2c over a 12-48V DC power bus.
Are their any current IC solutions that I could check out?
If not where would be a good place to start on such a ...
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1answer
104 views
i2c + 7 segement serial display + ATtiny85
I have a project that requires a 7 segment display and I was trying to get away with using the smallest micro controller possible.
Does anyone see any problems with connecting an ATtiny85 to a 7 ...
0
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1answer
72 views
Interfacing with an LCD screen
I have managed to salvage the LCD screen from an old Tom-Tom (the model number of the screen is LTE430WQ-F0B-0BS). It comes with a driver for the screen on the back, but it doesn't look humanly ...
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1answer
163 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 ...
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0answers
107 views
I2C Raspberry Pi to PIC24F
I'm new to PIC's and PIC programming but I'm working on a little project to try get a PIC24F32KA301 to communicate with a Raspberry Pi using I2C. The Raspberry Pi is the master and the PIC is the ...
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2answers
91 views
Determining I2C Address without Datasheet
When setting up I2C communications, I know that it is certainly ideal to have the devices' datasheet(s), and find the I2C address of the device(s) that way. However, in some reverse-engineering ...
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2answers
324 views
How to connect ATTiny45 to Arduino via serial/spi/i2c and send data?
I am trying to create a smart alarm system for my house. I want to have one arduino as the master and several other AtTiny's as slaves to collect data as temperature, moisture, gas concentration, ...
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1answer
155 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 ...
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3answers
245 views
Can this AVR MCU with 5V I2C work with this sensor with 3.3V I2C?
I'd like to interface an MPU-9150 sensor with an ATmega128 using I2C. The Atmega operates at 5V while the sensor chip operates at 3.3V.
How can I find out if the two can work together? I'm not very ...
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3answers
389 views
How to add additional I2C sensor module on Arduino
I have tried the GY-521 sensor on Arduino by using the guide from (http://playground.arduino.cc/Main/MPU-6050). It worked well. Can anyone guide me on how can I add another GY-521 module please? I am ...
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0answers
74 views
Burst mode data errors on I2C
I'm using burst mode to read 14 bytes from a sensor via I2C running at 400KHz. The problem is that there are periodic errors on the last byte of the packet, that come in roughly every 8 reads. The ...
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0answers
59 views
Altimeter module issues “i2c bad”
My altimeter module seems to go bad every once in a while and I can't figure out why. Seems like any minor impact to the module stops it.
It says "i2c bad" often and then seems like it works later? ...
2
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1answer
93 views
Bad clock pulse on I2C EEPROM read
I am seeing a strange behaviour on an I2C waveform, and it is causing an incorrect bit to be read by the master. The master device is an ET1200 EtherCAT ASIC, and my slave is a CY8C3666LTI PSoC which ...
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votes
1answer
119 views
How much max distance of SPI & USB & I2C and TWI(without any IC [closed]
How much max distance of SPI & USB & I2C and TWI(without any IC(my mean is directly)), and how can i amplify these?
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0answers
104 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 ...
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1answer
239 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 ...
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204 views
Msp430g2553 i2c communication library with itg3200 gyroscope
I've been creating an I2C library for communicating with ITG3200 gyroscope for MSP430g2553 experimental launchpad. I still have slight problems with sequential reading and the signed values but I'm ...
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2answers
125 views
On multi master i2c bus how to determine which device is the master of the bus?
On a multimaster i2c bus, how to determine which device started the transfer?
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1answer
171 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 ...
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44 views
Reading from an ITG-3200 Gyroscope
I'm having some trouble getting any reading from an I2C ITG-3200 Gyroscope breakout I'm using from Sparkfun. Here is the product: https://www.sparkfun.com/products/9801
I have a feeling this might be ...
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0answers
225 views
Msp430 I2C Single Byte Read Write
I have this code I've been working on that connects an ITG-3200 gyroscope slave and MSP430G2553 master via I2C bus. It was working fine yesterday but somehow today it is not working. I tried to debug ...
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1answer
99 views
What are some good older devices that I can scrounge i2c or spi modules from?
I am a newcomer to electronics design and I'd really like to start fiddling with making my own circuits. I have a raspberry pi which has both I2C and SPI interfaces, and I'm wondering if there's any ...
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2answers
199 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). ...
4
votes
2answers
181 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 ...
2
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1answer
2k views
Msp430 I²C single write-read example
I've been trying to use an I²C bus between a MSP430G2553 launchpad and ITG-3200 gyroscope breakout. Here is the Launchpad datasheet and user guide and the ITG-3200 datasheet. The ITG-3200 uses a ...
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votes
1answer
140 views
I2C protocol for PIC18F45K20 with C18 compiler
I'm currently trying to receive data from the 2-wire serial interface of an image sensor with a PIC18F45K20 written with C18 in MPLAB X IDE v. 1.41. How do I initialize the I2C protocol and how do I ...
2
votes
2answers
163 views
Does polling a DS1307 too frequently affect accuracy?
I did some research, and I found contradictory response on the web. I'm polling a DS1307 on an loop, with an Arduino, that takes about 20 ms to run, so basically I'm polling the I2C interface 50 times ...
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2answers
168 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 ...
4
votes
1answer
236 views
Problem with I2C EEPROM communication
I have a STM32L MCU connected to M24LR64E, an I2C EEPROM. Previously i had this setup working but then i changed some things (layout, firmware) and somehow i screwed the I2C and it is not working now.
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2answers
109 views
Dev Platform to talk to PMBus/SMBus/I²C Power Supplies
I am looking for a simple way to talk to PMBus power supplies (ie. get current information, turn power supply on or off, etc). This is normally integrated on computer main boards or server main ...
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3answers
196 views
Use 74LCX245 level transceiver for SPI / I²C
I need to convert the levels of the SPI and I²C busses of a 5 V microntroller to a 3.3 V card reader and EEPROM memory so I chose to use the 74LCX245 since it's a bidirectional transceiver.
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0answers
109 views
L3G4200D Gyroscope not sending ACK
I am working on interfacing to a L3G4200D Gyroscope breakout board .
I am using it in I2C mode, and the microcontroller I use is the 8051 (via bit banging).
I havent connected anything to the SDO ...
10
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2answers
219 views
I2C level shifting
I am currently designing a circuit that can record data from a sensor and save the data recorded into an EEPROM. My two devices (EEPROM and for testing purpose a RTC) are connected via an I2C bus to a ...
3
votes
3answers
237 views
At what point does crosstalk on I2C become a problem?
If I have a pair of I2C traces (SDA and SCL) on a 1 oz board, each being 8mil wide and separated by an 8mil gap, how long would the traces have to be before crosstalk would become an issue?
Edit:
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9
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7answers
881 views
I2C slave address not acknowledged (sometimes)
I'm trying to communicate with a remotely connected FRAM (FM24C04 from Ramtron) by using I2C. This memory is embedded on a board that can be inserted and removed at any time to/from the system ...
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4answers
483 views
Implementing an I2C buffer in C
I'm implementing a read-only I2C slave on a PIC18F4620. I have made a -working- ISR handler for the MSSP module:
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