On Tue, 23 Jan 2007, chan8337 wrote:
> According to the EP9301 user manual, i have written a sample code to
> read a voltage level on the GPI0 pin4 which is portC bit0. Once the
> code is running, i cant get a accurate result. Let say i set the input
> voltage to 1V but on the terminal the displayed voltage level keep
> varying.
>
> Maybe i missed something that must set in the registers.
> I have read the sample code provided from Embededarm website. But I
> cant understand it. It seem like I must correct the ADCResult with the
> caribration value stored inside the EEPROM.
>
> Anyone please help?
In my experience it is often more convenient and easier to use char *
pointer than int * - obviates the needs to adjust address offsets etc
>
> Just for your info my board is based on the EP9302-CQ cirrus arm
> processor. Is the register addresses inside the EP9301 user munual
> valid for EP9302?
>
> Below shows the code that i have written.
> --------------------------------------------------------------------
> #include<sys/types.h>
> #include<sys/mman.h>
> #include<stdio.h>
> #include<fcntl.h>
> #include<string.h>
>
> main(int argc, char **argv)
> {
> volatile unsigned int *SysSWLock, *ADCClkDiv, *DevCfg, *ADCSWLock,
> *ADCResult, *ADCSwitch, *PBDDR, *PBDR, *GPIOBDB;
> unsigned char *SysconBase, *ADCBase, *start;
>
> float ADResult;
> unsigned char state;
>
> int fd = open("/dev/mem", O_RDWR);
> SysconBase = mmap(0, getpagesize(), PROT_READ|PROT_WRITE, MAP_SHARED,
> fd, 0x80930000);
> ADCBase = mmap(0, getpagesize(), PROT_READ|PROT_WRITE, MAP_SHARED, fd,
> 0x80900000);
> start = mmap(0, getpagesize(), PROT_READ|PROT_WRITE, MAP_SHARED, fd,
> 0x80840000);
>
> /*Assign register addresses to pointers according to ep9301 user guide*/
> SysSWLock = (unsigned int *)(SysconBase + 0xC0);
> ADCClkDiv = (unsigned int *)(SysconBase + 0x90);
> DevCfg = (unsigned int *)(SysconBase + 0x80);
> ADCSWLock = (unsigned int *)(ADCBase + 0x20);
> ADCResult = (unsigned int *)(ADCBase + 0x08);
> ADCSwitch = (unsigned int *)(ADCBase + 0x18);
>
> PBDDR = (unsigned int *)(start + 0x14); //port b direction
> PBDR = (unsigned int *)(start + 0x04); //port b
> GPIOBDB = (unsigned int *)(start + 0xC4); // debounce on port b
>
> /*Setup the PortB to received digital input*/
> *PBDDR = 0xf0; //upper nibble output, lower nibble input
> *GPIOBDB = 0x01; //enable debounce on bit 0
>
> /*Steps to setup the onboard ADC for ts-7200*/
> *SysSWLock = 0xAA; //unlock the software lock for the all registers
> *ADCClkDiv |= 0x80010000; //enable TSEN(bit32)-AD clock start, enable
> ADIV(bit16)-AD clk/4
>
> *SysSWLock = 0xAA; //unlock the software lock for the all registers
> (AGAIN)
> *DevCfg |= 0x00020000; //Set the ADCEN - ADC enable.
>
> *SysSWLock = 0xAA; //unlock the software lock for the all registers
> (AGAIN)
> *DevCfg &= 0xFFFFFFFB; //Clear the ADCPD-ADC. Set 1 to Power Down
>
> *ADCSWLock = 0xAA; //unlock the software lock for the all registers
> (AGAIN)
> *ADCSwitch = 0x00000608; //Enable AD channel 4 to receive analog signal.
>
> /*do while loop is terminated when portb bit0 is "0". Default pull up
> to logic "1"*/
> do
> {
> state = *PBDR;
> while((*ADCResult & 0x80000000)==0x80000000); //pooling until
> bit31 set then exit.
> ADResult = ((float)(*ADCResult & 0x00000FFF)/4095)*3;
> printf("Channel 0 Result: %f \n", ADResult);
>
> }while(state & 0x01);
>
> close(fd);
> return 0;
>
> }
>
>
>
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