Hello,
I am new for GPIB and I start from test from "Using the TNT4882 in an 8051-Family Microcontroller-Based System". We use AT32UC3A microcontroller and I rewrite test in C. FIFOA and FIFOB test running without error. When programm test NFF and NEF interrupts I receive error. Debugging show that both interrupts work fine, there is error reading data from FIFOB (test programm request NFF interrupt and interrupt handler push 2 bytes to FIFOB. then test request NEF and handler read 2 bytes from FIFOB). Programm push 0x55 and 0xaa, hadler read 0xf2 0xaa. I try different things - nothing change, finally I push 3 bytes to FIFOB - dummy 0x50, then 0x55 and 0xaa. this time I read correct 2 bytes in handler - 0x55 and 0x55. Please note that just before interrupt test FIFOA and FIFOB was tested writing -reading with data range0-255 without error. There is a source code of the interrupt test (I leave original procedures descriptions from app note):
//************************************************************************//
//* Module : INT_TST *//
//* Description : Performs Interrupt Test. *//
//* *//
//* Reference : MCS51 & TNT4882 Application Notes. *//
//************************************************************************//
//************************************************************************//
unsigned char int_tst_4882(void)
{
unsigned char i;
errorTNT=0;
printString("waiting for NFF interrupt...", 50, 220, GREEN, (U8 *)&pfont[0]);
tnt[(IMR3<<2)| BASE]=0x08; //Write interrupt bit NFF to interrupt register
//wait until it become 0
do{i=tnt[(IMR3<<2)| BASE];}while((i&0x08)!=0);
printString("waiting for NEF interrupt...", 50, 230, GREEN, (U8 *)&pfont[0]);
tnt[(IMR3<<2)| BASE]=0x04; //Write interrupt bit NEF to interrupt register
do{i=tnt[(IMR3<<2)| BASE];}while((i&0x04)!=0);
return(errorTNT);
}
//************************************************************************//
//************************************************************************//
//* Module : HANDLER *//
//* Parameters : NONE *//
//* Description : Interrupt Handler. This routine is entered when the *//
//* TNT chip asserts its interrupt signal. The interrupts*//
//* should be enabled for interrupts to occur. *//
//* The handler handles two cases of interrupts. These *//
//* cases are INPUT, and OUTPUT. *//
//************************************************************************//
//************************************************************************//
//==================================================================================================================
//interrupt.
//in this procedure we will handle interrupt from TNT4882
//X-Y coordinates of the touch panel
__attribute__((__interrupt__))
static void gpio_pb28_int(void)
{
unsigned char i,a;
//printString("Interrupt active", 50, 210, GREEN, (U8 *)&pfont[0]);
i=tnt[(IMR3<<2)| BASE];
a=tnt[(ISR3<<2)| BASE];
if ((i & a & 0x08)!=0x08)
{ //maybe NEF?
if ((i & a & 0x04)!=0x04)
{
errorTNT=1;
goto intend;
}
i=i & 0xFB; //reset NFF flag and put it back
tnt[(IMR3<<2)| BASE]=i;
//read data from FIFOB
a = tnt[(FIFOB<<2)| BASE]; //Read $55 from FIFOB
i = tnt[(FIFOB<<2)| BASE]; //Read $AA from FIFOB
if (a!=0x55 || i!=0xaa)
{
errorTNT=1;
goto intend;
}
}
else //NFF
{
i = i & a & 0xF7; //reset NFF flag and put it back
tnt[(IMR3<<2)| BASE]=i;
tnt[(CMDR<<2) | BASE]=0x10; //Reset FIFOs
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!/DUMMY WRITE FOR UNKNOW REASONS
tnt[(FIFOB<<2)| BASE]=0x50; //DUMMY WRITE FOR UNKNOW REASONS
tnt[(FIFOB<<2)| BASE]=0x55; //Write $55 to FIFOB
tnt[(FIFOB<<2)| BASE]=0xaa; //Write $AA to FIFOB
}
intend:
gpio_clear_pin_interrupt_flag(GPIO_PIN_INT); //Reset INT state of the input pin
}
May be someone can explain what and why happen - why I did not read original data and should write "dummy" byte?
Thank you very much in advance for your help and support!
