基于GPIO的I2C模拟主设备通信源码详解

/*
Note : At switch I2C_SDA

$ I2C_SDA Low, Out : Error

$ I2C_SDA Out, Low : OK
*/

System_Clock => 8000000; // User defined, ref. CLKMD, maybe 4/8/16-000000 or other ...
FPPA_Duty => 16; // User defined, ref. PMODE, maybe /2, /4, /8, /16

// T_xxx => xxx nS
T_High => 4700;
T_Low => 4700;
T_Start => 4700;
T_Stop => 4700;
T_Buf => 4700;
Delay_High => T_High ?  (((System_Clock / FPPA_Duty) / (1000000000 / T_High)) + 1) : 0;
Delay_Low => T_Low ?   (((System_Clock / FPPA_Duty) / (1000000000 / T_Low)) + 1) : 0;
Delay_Start => T_Start ? (((System_Clock / FPPA_Duty) / (1000000000 / T_Start)) + 1) : 0;
Delay_Stop => T_Stop ?  (((System_Clock / FPPA_Duty) / (1000000000 / T_Stop)) + 1) : 0;
Delay_Buf => T_Buf ?   (((System_Clock / FPPA_Duty) / (1000000000 / T_Buf)) + 1) : 0;

//#if (Delay_High >= 256) || (Delay_Low >= 256)
// .ERROR I2C_Delay is %Delay_High, %Delay_Low, and >= 256
// .ENDP
//#endif

Easy_Delay macro val, cmp

#IF val > cmp
.delay val - cmp;
#ENDIF
endm

I2C_SDA BIT PB.5;
I2C_SCL BIT PB.4;

static void I2C_Write_Acc (void)
{
BYTE data, count;
data = ~ A;
count = 8;

do
{
$ I2C_SCL Low; // 1
sl data; // 2
#if _SYS(OP:SWAPC IO.N)
swapc _PXC(I2C_SDA); // 3
$ I2C_SDA Low; // 4
Easy_Delay (Delay_Low, 4);
#else
if (!CF) $ I2C_SDA In; // 34
if (CF) $ I2C_SDA Out; // 56
$ I2C_SDA Low; // 7
Easy_Delay (Delay_Low, 7);
#endif

$ I2C_SCL High; // 1