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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55 views
Unable to understand how to use bq27200 (i2c)
I am working on getting a Raspberry pi to communicate with a bq27200 ("SINGLE CELL Li-Ion AND Li-Pol BATTERY GAS GAUGE IC FOR PORTABLE APPLICATIONS").
I not sure I am using the correct method to ...
1
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1answer
84 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 ...
0
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2answers
71 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
55 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 ...
0
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1answer
69 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
55 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 ...
0
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2answers
60 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 ...
1
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2answers
160 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, ...
1
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1answer
123 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 ...
3
votes
3answers
143 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 ...
1
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3answers
146 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 ...
1
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0answers
64 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 ...
0
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0answers
49 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
votes
1answer
68 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
92 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
91 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
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1answer
165 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
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0answers
101 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 ...
2
votes
2answers
82 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?
2
votes
1answer
128 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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0answers
36 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 ...
1
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0answers
151 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 ...
2
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1answer
91 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 ...
0
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2answers
158 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
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2answers
140 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
votes
1answer
1k 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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1answer
112 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 ...
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2answers
120 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
129 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
186 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
80 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 ...
2
votes
3answers
150 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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2
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0answers
95 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
196 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
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3answers
196 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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8
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7answers
709 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 ...
4
votes
4answers
372 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:
...
2
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2answers
241 views
I2C pull-up resistors calculation & where to place them
I'm connecting a PIC18F46K22 (master) to a PIC18F4620 (slave) using I2C. The wire between the devices is ~30cm. I'm using 400kHz without slew rate control. Later on, I'll add another 18F4620 on ~5cm ...
8
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1answer
259 views
What is slew rate for I2C?
I'm configuring I2C on a PIC18 using the built-in functions of the C18 compiler as described in section 2.4 of the documentation:
...
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1answer
73 views
DS1077 to drive a PIC's clock
I found the DS1077, a "dual-output, programmable, fixed-frequency oscillator". I was wondering if it would be possible to let this chip provide the clock signal for the PIC(18F46K22) that operates the ...
1
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1answer
144 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 ...
1
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1answer
160 views
Cheapest AVR With Built in I2C Support
I'm looking to build a pretty basic project that relies on several submodules that use I2C for communication. I'm trying to find the smallest, cheapest AVR device that supports I2C. I know the 328P ...
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0answers
132 views
Level shifting with BSS138 - weird values
I need to connect 5V and 3.3V devices via I2C as follows:
I've connected 3.3V and 5V pull-ups and try to measure voltage. There is 5V on HV and TX_HV but 4,7V on LV / TX_LV.
Putting TX to LOW ...
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1answer
67 views
understanding how to set values when using all 8 bits from one address plus the next 2 of the next address
I hope that I am phrasing this correctly but here goes. I have been building a service for MSRDS to run my prototype board. People have probably seen me ask questions about this before. I have been ...
0
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2answers
273 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: ...
6
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2answers
157 views
Help to identify unknown Sync Serial Bus
Has anyone seen a sync serial bus communication like this?
Repeated Pattern :
Detail of beginning :
Personally, I haven't been able to figure it out myself...
It seems like I2C, however:
The ...
1
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1answer
106 views
I2C maximum bus speed calculation
This question is based on the Philips I2C specification UM10204.They gave (section 7.2.1, page 56) for calculating the maximum frequency of the bus:
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1
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1answer
68 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 ...
7
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4answers
127 views
i2c mixed frequency possible?
Suppose we have a 400 kHz i2c bus. There is one master and a bunch of slave devices. We would like to introduce one more slave device, but unfortunately it only goes to 100 kHz .
Clearly, the solid ...
0
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3answers
187 views
Converting two's complement hex values to binary?
I'm reading x-axis accelerometer data from an IC via the I2C bus using I2C-Tools ( specifically i2cget ) in Linux. Here is the code that is reading these values:
...
