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 on PIC12s using MPLAB x (win7) and XC8
I am from a programming background, but very new to microcontrollers. Pardon me if this question is very basic, or doesn't make complete sense. I'm trying to bootstrap my knowledge, and the learning ...
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1answer
53 views
MCP23017 in series
I have a hand full of MCP23017 (16 bit multiplexers/ I/O Expander) but I can only get 8 IC on the bus due to the limit of address but I need 200 pins (about 13 ICs) for a 8*8*8 RGB cube
and was ...
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1answer
56 views
Acknowledge polling in EEPROM
I am using C18 compiler and I learned that acknowledge polling feature will greatly help in reducing the write time that is to remove the fixed delay in traditional methods. Well I am using EEPROM ...
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1answer
42 views
Is it possible to only utilise SMBus on PCI Express 1X?
According to the Wikipedia page on PCI Express, the PCI-e 1X slots have 18 pin positions on two lanes (so 36 pins) and positions 5-9 represent SMBus and JTAG.
I'd like to hook up a µC as an ...
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3answers
130 views
Increase GPIO outputs
I'm working on a project in which I need 32 outputs from an MCU that only has 8 free outputs.
To accomplish my goal I have the following requirements:
I must be able to toggle more than one output ...
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1answer
54 views
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25 views
I2C pic32 slave with two address [duplicate]
I'm developping for a pic32 plateform. My application consists to realise I²C communication between µC 8051 and PIC32. The 8051 is the master and the PIC32 is the slave. I have established a I²C ...
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2answers
114 views
PIC 32 two I²C slave address
I'm developping for a pic32 plateform. My application consists to realise I²C communication between µC 8051 and PIC32. The 8051 is the master and the PIC32 is the slave. I have established a I²C ...
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1answer
84 views
I2C delay needed and c18
I am using I2C and I have earlier posted doubts about I2C here. I am using PIC controllers and using their compiler C18. I used their libraries to build a function to write data in EEPROM via I2C, and ...
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2answers
114 views
I2C and SPI Bus Routing
When routing an I2C (SDA, SCL) bus or SPI (SCLK, MOSI, MISO) bus to multiple slaves is it preferred to wire the slaves in parallel or series? Below are two diagrams with distances labeled to help with ...
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1answer
46 views
I2C Pull-ups with Multiple Power Supplies
If I have an I2C Master with multiple I2C Slaves all on separate 3V3 lines (ie 3v3_Master, 3V3_Slave1, 3V3_Slave2...ect) does it matter which 3V3 line the pull-up resistors on the line connect to?
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44 views
I2C communication issue in stack boards assembly
We have a stack of two boards. There an I2C signal is running between two boards through Board to board connectors.
I2C signal is not working properly for all associated peripherals assembled on lower ...
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3answers
75 views
High-Side Current Sensing; I2C
I am beginning a project that requires the sensing of a very small current (in the nA range) from a 3000V supply. The application is such that it can only be done on the high side. The data needs to ...
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2answers
62 views
Weird reading from NAU7802 ADC
I'm using an NAU7802 ADC which has a built in amplifier. I'm trying to use it to read a strain gauge but it keeps giving me weird readings.
Eventually I resorted to shorting the two differential ...
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1answer
111 views
Two wire serial interface or i2c?
I am trying to connect with mrk2 core(nxp pcf7941) in monitoring and debug mode.datasheet says the communication protocol is "Two wire serial interface (MSDA/MSCL)" . It looks like i2c but Saleae ...
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1answer
99 views
I2C clock frequency variations
I am using an I2C peripheral in PIC18 series running at 100 kHz and I have used pull up resistors of 4.7 k\$\Omega\$ in the process. I then loaded a code with continuous write operation of EEPROM and ...
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1answer
91 views
Debug of data transmission via I2C
I was able to generate I2C transmission through micro controller but still i have a doubt on certain things.
First being, if we send a data like 0x0a, then we can monitor the data as it is a single ...
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2answers
116 views
Can ATmega88 be run at 3.3V with internal clock?
I want to use a few ATmega88s with Arduino bootloaders to act as I2C stepper drivers and temperature controllers that will interface with a Raspberry Pi. The thing is just that it seems the RPi ...
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1answer
143 views
I2C function for PIC
I wrapped a function for I2C initialization on PIC18F26J50 and it happens to be somewhat like this:
...
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3answers
119 views
Why only 127 slaves in I2C?
Since the slave addresses are 7 bits long, why is it that the number of slaves can be only 127? Is one of the addresses reserved for some special purpose?
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1answer
189 views
i2c over gpio - level shifter
I'm quite new to this. I have just basic background in electronics. So I would appreciate an advice from someone more experienced.
I would like to connect an i2c display to my tp-link wr703n (ar9331) ...
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3answers
156 views
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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4answers
176 views
i2C : pull-up resistors “design pattern”, Shielded 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 ...
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1answer
83 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
63 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
87 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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57 views
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
211 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 ...
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3answers
128 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
166 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 ...
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1answer
245 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 ...
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1answer
76 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
189 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
180 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 ...
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1answer
128 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 ...
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1answer
178 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
148 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 ...
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1answer
100 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
302 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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1answer
219 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
164 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
543 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
209 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
386 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
1k 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
91 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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63 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? ...
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1answer
129 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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1answer
194 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
119 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 ...
