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David_K
Joined: 14 Nov 2006
Posts: 5
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| I²C and Streams |
 Posted: Thu Nov 16, 2006 12:17 pm |
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I have 2 Smart Batteries in my system and I need to communicate with them through I²C. Because they have the same address I need to have separate pins for each battery. I did this on another project a couple of years ago and I had to write 2 copies of all my functions.
They started out like this:
| Code: | #use i2c( Master, sda=PIN_B2, scl=PIN_B1 )
#separate
unsigned long ReadLongRegister_B( int &BatteryRegister ) {
unsigned int LowByte, HighByte;
const int SMBusBatteryWrite = 0x16;
const int SMBusBatteryRead = 0x17;
i2c_start();
i2c_write(SMBusBatteryWrite);
i2c_write(BatteryRegister);
i2c_start();
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Followed by the next one:
| Code: | #use i2c( Master, sda=PIN_C4, scl=PIN_C3, FORCE_HW )
#separate
unsigned long ReadLongRegister_A( int &BatteryRegister ) {
unsigned int LowByte, HighByte;
const int SMBusBatteryWrite = 0x16;
const int SMBusBatteryRead = 0x17;
i2c_start();
i2c_write(SMBusBatteryWrite);
i2c_write(BatteryRegister);
i2c_start();
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I would really like to use the StreamID option and simplify things but I can't seem to get it right. I am rusty, it's been over 2 years since I did any serious programming and I'm just now getting spun back up.
Here's how I tried using streams:
| Code: | unsigned long ReadLongSMBusRegister( const int MyStreamID, int &BatteryRegister ) {
unsigned int LowByte, HighByte;
const int SMBusBatteryWrite = 0x16;
const int SMBusBatteryRead = 0x17;
i2c_start(MyStreamID);
i2c_write(MyStreamID, SMBusBatteryWrite);
i2c_write(MyStreamID, BatteryRegister);
i2c_start(MyStreamID);
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but the compiler doesn't like me passing a constant.
I think I'm stuck with writing 2 sets of functions I just don't have to include the #use for each one, otherwise it's the exact same thing.
Comments? Help? Flames?
David |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Nov 16, 2006 1:35 pm |
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| What is your compiler version ? |
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David_K
Joined: 14 Nov 2006
Posts: 5
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| Posted: Thu Nov 16, 2006 2:04 pm |
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| I'm using 4.014. The part is a 18F4685. I'm using software I²C. |
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rnielsen
Joined: 23 Sep 2003
Posts: 852
Location: Utah
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| Posted: Thu Nov 16, 2006 3:06 pm |
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I've had to use multiple I2C devices, that had the same address, on the same bus before. I used a FET MUX switch (SN74CBT3253) and had two pins, from the PIC, select which pair of fets fed the I2C signals through. If you try this make sure you have pull-ups on each of the output side for each I2C device, along with pull-ups on the PIC side, or the device will see an extra pulse when that channel is de-selected. Just have your PIC select which MUX pins to use before each command sequence.
Ronald |
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