Hello guys, forst post in here, please be kind. I am recently 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 PICKIT3 http://www.kynix.com/Detail/954152/PICKIT3.html . We've got a few other peripherals all working so far, including a 20x4 LCD also over I2C, so at least that is working. Our issue is that our DAC operates on and outputs 5V, regardless of whether or not we have a Vref connected. (the chip defaults to short Vref to Vdd if nothing is connected to the pins)
The output from the DAC goes to a voltage follower that controls a power MOSFET, allowing a variable amount of current to flow to the battery based upon readings from a current sensor (in-line) and voltage sensor across the battery terminals.
Relevant code snippets are attached below:
#define DAC 0x60
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// Configure I2C registers
void ConfigI2C
{
//1 USES RD10 AS SCL1 AND RD 9 AS SDA1
/// I2CxCON I2CxSTAT I2CxADD I2CxMSK I2CxTRN I2CxRCV
I2C1BRG=0x186; //390 for 80MHz to 100KHz
I2C1CONbits.A10M=0; //Use 7-bit addresses
I2C1CONbits.DISSLW=1; //disable slew control for standard
I2C1CONbits.ACKDT=0; //Use and ACK not NACK
I2C1ADD=22; //Sets slave address for PIC32
TRISD=0; //Sets Port D to output
I2C1CONbits.ON=1; //turn on I2C
}
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// Start
void I2C_start(void)
{
I2C1CONbits.SEN=1; //send start
while(I2C1CONbits.SEN){} //waits till start bit detected
}
void I2C_stop(void)
{
I2C1CONbits.PEN=1; //send stop
while(I2C1CONbits.PEN){} //waits till stop bit detected
}
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.
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void SendI2C3(char addrs,char regis, char data)
{
char ack;
I2C_start;
ack=I2C_write(addrs); //Address for LED is 0x50
ack=I2C_write(regis); //0xFE for LED
ack=I2C_write(data); //0x20to0x7F standard
I2C_stop;
}
We just get Vref out. We've tried all 8 address the board can have, and no dice.
Anybody have any advice on how to help me? I've been stuck on this problem for a couple of days.
Thanks all advice.
The output from the DAC goes to a voltage follower that controls a power MOSFET, allowing a variable amount of current to flow to the battery based upon readings from a current sensor (in-line) and voltage sensor across the battery terminals.
Relevant code snippets are attached below:
#define DAC 0x60
.
.
.
// Configure I2C registers
void ConfigI2C
{
//1 USES RD10 AS SCL1 AND RD 9 AS SDA1
/// I2CxCON I2CxSTAT I2CxADD I2CxMSK I2CxTRN I2CxRCV
I2C1BRG=0x186; //390 for 80MHz to 100KHz
I2C1CONbits.A10M=0; //Use 7-bit addresses
I2C1CONbits.DISSLW=1; //disable slew control for standard
I2C1CONbits.ACKDT=0; //Use and ACK not NACK
I2C1ADD=22; //Sets slave address for PIC32
TRISD=0; //Sets Port D to output
I2C1CONbits.ON=1; //turn on I2C
}
.
.
.
// Start
void I2C_start(void)
{
I2C1CONbits.SEN=1; //send start
while(I2C1CONbits.SEN){} //waits till start bit detected
}
void I2C_stop(void)
{
I2C1CONbits.PEN=1; //send stop
while(I2C1CONbits.PEN){} //waits till stop bit detected
}
.
.
.
void SendI2C3(char addrs,char regis, char data)
{
char ack;
I2C_start
;ack=I2C_write(addrs); //Address for LED is 0x50
ack=I2C_write(regis); //0xFE for LED
ack=I2C_write(data); //0x20to0x7F standard
I2C_stop
;}
We just get Vref out. We've tried all 8 address the board can have, and no dice.
Anybody have any advice on how to help me? I've been stuck on this problem for a couple of days.
Thanks all advice.
