[SOLVED] Software / Bit-bang I2C library for Energia

[Rei Vilo 695]

The P1_6 and P1_7 pins are already used for SPI and I need an I2C connection.

 

So I'm looking for a bit-bang I2C library, for Energia.

 

I've found RobG library at http://forum.43oh.com/topic/441-serial-eeprom/?p=3876 but I'm facing big issues when I try to port it to Energia.

 

Thank you for your help.

[Rei Vilo 695]

I've found detailed documentation on ti.com website MSP430 Interface to TPS60250 via I2C Master Software with

• detailed PDF http://www.ti.com/litv/pdf/slva302
  
• code http://www.ti.com/litv/zip/slva302
  

Unfortunately, the code requires to be translated into Energia.

 

Thank you for your help.

[roadrunner84 466]

It shouldn't, the code is built for CCS or IAR. Energia is based upon GCC. Only the way interrupts are mapped should require translation. Most registers are mapped identical no matter the compiler. Very litte changes should be required to get it working on Energia.

[energia 485]

That implementation is only for USI. It would work for the 2452 and 2231 (or any MSP430 that features an USI). 

I2C is more difficult to bit-bang than SPI so if you do not need the speed on SPI then it's way easier to bit-bang SPI and use the hardware for I2C.

[Rei Vilo 695]

Thank you for the answer. Actually, it is for the 2553.

[calinp 24]

Hi Rei,

I found a I2C software lib for Arduino and after making the necessary changes it seems to work. At least it detects the address range of a small eeprom using the included example.

The original with more examples is at http://forums.adafruit.com/viewtopic.php?f=25&t=13722

 

Calin

I2cMaster.zip

[Rei Vilo 695]

Thank you!

[Rei Vilo 695]

After a lot of work, especially with a logic analyser, I changed the delay functions for the more precise

 

#define TICKS_PER_MS (F_CPU / 1000)
#define TICKS_PER_US (TICKS_PER_MS / 1000)

///
/// @brief	delayI2Cms
/// @param	delay number of milliseconds
///
void delayI2Cms(uint16_t delay)

{
    while (delay--) __delay_cycles(TICKS_PER_MS);
}

///
/// @brief	delayI2Cus
/// @param	delay number of microseconds
///
void delayI2Cus(uint16_t delay)
{
    while (delay--) __delay_cycles(TICKS_PER_US);
}

 

After many tests, the library is available at http://forum.43oh.com/topic/3619-energia-library-software-i%C2%B2c-master-for-msp430g2553/?p=32365'>[Energia Library] Software I

[L.R.A 78]

this is to work with i2c sensors, bus, and that kind of slaves? i've been trying to work with a srf10 but i can only get ranges until 40cm

[Rei Vilo 695]

This library only implements I

[L.R.A 78]

dam ricky! got me again! he told me that i could use it with no problem with msp430. gotta see those 5V/3.3V logic converters. You know any good?

 

Thanks!

 

would this work if i use both TX lines?? https://www.sparkfun.com/products/8745

[Rei Vilo 695]

LRA: please have a look at http://embeddedcomputing.weebly.com/isup2c-logic-level-converter.html'>I

[L.R.A 78]

Pretty nice. With the short time we have i wasn't in the mood to study the circuit or search so i was just gona buy it. Your mosfet based circuit is pretty nice and easy to make and also cheapper.

 

Thanks

[Rei Vilo 695]

You're welcome! The MOSFET circuit is very reliable as it doesn't pack extra-features ICs may include.

 

I use it for the smart sensors I've developed for my industrial robots and models built with the fischertechnik system.

 

This colour recognition sensor is based on a MSP430 and talk through I

[L.R.A 78]

hehe i was actualy looking at that sensor before.

 

a litle question. If the stellarpad is 5V tolerant does it mean i don't need that circuit to interface the srf10?

 

and is there anyway that works with analog signals? changing from 5V to 3.3V MCU is kinda of a pain