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.
1
vote
1answer
33 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
0answers
21 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
53 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
54 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
0answers
24 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
vote
0answers
46 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
votes
1answer
69 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
votes
1answer
76 views
Multiplex two I2C ICs into four 7 Segment displays
I currently have two PCF8574AN I2C 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). I have thought ...
0
votes
1answer
77 views
Ideal protocol to read parameters (ex Temperature, voltage, battery status of satellite) from STM32 microcontroller? [closed]
I'm working on an nano satellite project. The task assigned to me is in the Checkout-system module of the satellite.
A couple of parameters from the STM32 microcontroller which will be mounted on the ...
4
votes
2answers
106 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
129 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 ...
-2
votes
1answer
63 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 ...
1
vote
2answers
95 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 ...
0
votes
2answers
85 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
96 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.
...
0
votes
1answer
36 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 ...
-1
votes
0answers
62 views
When the I2C is failure, is there a probability for the product to stop at some points? [duplicate]
Recently，my colleague met a problem,I2C communication is dirrupted under heavy interrupt load, using the STM32.
The following post has a detailed discription related on the problem:
I2C read/write ...
1
vote
3answers
84 views
Use 74LCX245 level transeiver for SPI / I2C
I'm needing to convert the levels of the SPI and I2C busses of a 5v microntroller to a 3.3v card reader and epprom memory so I choosed to use the 74LCX245 since its a bidirectional transeiver.
But ...
2
votes
0answers
74 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
votes
2answers
154 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
147 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:
...
8
votes
7answers
392 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 ...
3
votes
4answers
259 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
votes
2answers
109 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 ...
7
votes
1answer
102 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:
...
1
vote
1answer
55 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
vote
1answer
104 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
vote
1answer
118 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 ...
1
vote
0answers
86 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 ...
0
votes
1answer
63 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
votes
2answers
149 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: ...
4
votes
0answers
100 views
Help to identify unknown Sync Serial Bus
Does somebody already seen a sync serial bus communication like that ?
Repeated Pattern :
Detail of beginning :
I fail to identify it...
it look like I2C but :
it have a clock at 2MHz (so ...
1
vote
1answer
76 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:
...
1
vote
1answer
56 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
votes
4answers
110 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
votes
3answers
101 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:
...
0
votes
0answers
51 views
Library for multi-master comunication of two ATTinys 261/461/861 I2C/SPI
I am building device with two ATTiny 461 connected by about 60 cm long cable. I need ATTinys to send/receive only few bytes once a time. Random time, random direction. I would like multi-master ...
2
votes
1answer
397 views
Best way to communicate Raspberry Pi and ATTiny13
What is best way to connect two or three microcontrollers, ATTiny13 to Raspberry-Pi and get master (Raspberry Pi) communication? Are there any ready libraries for ATTiny13 for SPI or I2C? Maybe some ...
1
vote
2answers
93 views
I2C with PIC32 and MCP4706 Not Working
We're working on a battery charger for an electric bicycle at the moment, but prototyping with a PIC32MX695F512H kit board and an MCP4706 DAC soldered onto a breakout board, programmed using a ...
0
votes
1answer
52 views
I2C on explorer 16 board not working
I am using the Explorer 16 Board for building a Accel connected by I2C .
Currently I have only the I2C part done and I am trying to tap scl1 & sda1 using oscilloscope. The accel has to connected ...
1
vote
1answer
157 views
Bit Bang to I2C EEPROM MSP430
I found some code to Bit Bang to an EEPROM on the MSP430 here, but if I change the pins to what is on my design it fails to read and write. I've also added a LED for output this should blink if it ...
5
votes
2answers
96 views
i2c external pullup kills communication
I am using an MCP23017 (which shouldn't matter tho) to extend the number of GPIO pins of an arm based linux computer using i2c-dev bitbanging. It all works fine with wires of a few centimetres.
The ...
3
votes
1answer
74 views
i2c bus capacitance
It is given in philips i2c specification that maximum number of devices connected to the bus is limited by bus capacitance.There is formula specified for pull up resistor but there is no formula to ...
3
votes
2answers
74 views
i2c bus electrical specification
Rise time and Fall time of both SDA and SCL signals are given as 20 + 0.1Cb ns in I2C bus fast mode electrical specifications version 2.1. Cb is bus capacitance and units in picofarad. How do the ...
0
votes
0answers
56 views
MinIMU9 v-2 and LPCxpresso
With regards to the post:
Two MinIMU-9 v2 with LPCxpresso, or Arduino Uno/Mega
I decided to interface two MinIMU v2 with my LPCxpresso. After googling for a while, I have found that thread, in which ...
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 ...
1
vote
2answers
135 views
Two MinIMU-9 v2 with LPCxpresso, or Arduino Uno/Mega
I am working on a project that interfaces two IMU sensors to one microprocessor (NXP LPCxpresso). The purpose is to read both of gyro and accelero at two different place on the bodies. I have ...
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:
...
5
votes
1answer
152 views
i2c on different logic level devices
I'm having a problem making LPC2148 work with SRF10 sensor. LPC is 3.3v device with 5v compatible i2c (at least user docu claims that). On the other side there is SRF10 device which is 5v.
I have ...
2
votes
3answers
204 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 ...
