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kd5uzz
Joined: 28 May 2006
Posts: 56
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| I2C and Serial at the same time on the 16F88 |
 Posted: Thu Mar 06, 2008 11:14 pm |
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Hello,
I've created an 8 channel servo controller that operates on a shared serial bus. I have two of these boards. I want to control these boards from a Wii Nunchuck. I am trying to create a board that will read the nunchuck data via I2C and format it correctly for the Servo controller's serial bus. Looking at the pinout of the 16F88 I was under the impression that I would be able to use the serial pins (and hardware UART) as well as the I2C pins at the same time. I've already created a PCB based on this assumption. When I run the code listed below, and have FORCE_HW in the #USE I2C line I get 255 returned from all channels of the nunchuck. This leads me to believe a HW problem with the nunchuck (much of this code was copied from a project I did on an 16F876a that worked fine. Thanks again PCM!). If I omit the FORCE_HW then I get 46. I don't understand the reason for the difference. I've tried adding FORCE_SW to the #USE RS232 line, no change. So, is this an issue of trying to use two pieces of HW at the same time, or do I have another problem?
| Code: | #include <16F88.h>
//#build(reset=0x1, interrupt=0x5) // Necessary for Bootloader
//#ORG 0x0F00,0x0FFF {} // Necessary for Bootloader
#fuses NOWDT,NOPROTECT,NOBROWNOUT,NOLVP, NOMCLR, INTRC
#use delay(clock=8000000)
#use rs232(stream=Jech_Bus, baud=19200, xmit=PIN_B5, rcv=PIN_B2)
#use i2c(Master, sda=PIN_B1, scl=PIN_B4,FORCE_HW)
#define NUNCHUCK_I2C_WRITE_ADDR 0xA4
#define NUNCHUCK_I2C_READ_ADDR 0xA5
int8 nunchuk_decode_byte (char x);
void nunchuck_read_data(int8 *buffer);
void nunchuck_init(void);
void main(){
int8 buffer[6] = {0};
printf("16F88 Nunchuck Test\n\r");
nunchuck_init();
delay_ms(100);
while(TRUE){
delay_ms(100);
nunchuck_read_data(buffer);
printf("X:%U\n\r",buffer[0]);
}
}
//the following nunchuck routines are from PCM Programmer on the CCS forums..Thanks!
int8 nunchuk_decode_byte (char x)
{
x = (x ^ 0x17) + 0x17;
return x;
}
void nunchuck_init(void)
{
i2c_start();
i2c_write(NUNCHUCK_I2C_WRITE_ADDR);
i2c_write(0x40);
i2c_write(0x00);
i2c_stop();
}
//---------------------------------
void nunchuck_read_data(int8 *buffer)
{
i2c_start();
i2c_write(NUNCHUCK_I2C_WRITE_ADDR);
i2c_write(0);
i2c_stop();
delay_us(150); // This delay is necessary.
i2c_start();
i2c_write(NUNCHUCK_I2C_READ_ADDR);
buffer[0] = nunchuk_decode_byte(i2c_read());
buffer[1] = nunchuk_decode_byte(i2c_read());
buffer[2] = nunchuk_decode_byte(i2c_read());
buffer[3] = nunchuk_decode_byte(i2c_read());
buffer[4] = nunchuk_decode_byte(i2c_read());
buffer[5] = nunchuk_decode_byte(i2c_read(0));
i2c_stop();
}
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Matro
Guest
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| #use_i2c initiliazation |
| Posted: Fri Mar 07, 2008 2:21 am |
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Your "#use_i2c" configures the 16F88 i2c as Master while it's only capable to be a Slave.
Maybe here is the problem. ;-)
Bye. |
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Ttelmah
Guest
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| Posted: Fri Mar 07, 2008 3:34 am |
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It ought to work, if he gets rid of the 'FORCE_HW' keyword. As you say, the 16F88, has a hardware slave, but requires a software master. 'FORCE_HW', forces code for the I2C hardware to be generated, which this chip doesn't have for master operation. Really ought to give an error message.....
Best Wishes |
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kd5uzz
Joined: 28 May 2006
Posts: 56
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| Posted: Fri Mar 07, 2008 9:06 am |
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| When I remove the FORCE_HW (and remove the nunchuck_decode bit) I get 0's. |
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