Jonathan Cameron schrieb:
> A driver that should work with this chip is part of the
> iio subsystem, so I have a fair bit of familiarity (though
> only via 1238 rather than this exact model)
I found this subsystem too and its promising, but it depends on RTC with
periodic Interupts - and most of embedded hardware lacks of such RTCs.
is it possible to attach a ds1307 for this reason?
> Done a bit of digging around and my original test code was
>
> #include <fcntl.h>
>
> #include "i2c-dev.h"
>
> int main(int argc, char* argv[])
> {
>
> struct i2c_smbus_ioctl_data arg;
> union i2c_smbus_data data;
> int adaptor_nr=atoi(argv[1]); //check this
> char filename[20];
> sprintf(filename,"/dev/i2c-%d",adaptor_nr);
>
> int file;
> if((file = open(filename, O_RDWR))<0)
> {
> printf("could not open /dev/i2c-%u\n", adaptor_nr);
> exit(-1);
> }
> if(ioctl(file,I2C_SLAVE, 0x34) < 0)
> {
> printf("could not set slave address \n");
> return -1;
> }
>
> arg.size = I2C_SMBUS_BYTE;
> arg.read_write = I2C_SMBUS_WRITE;
> arg.command = I2C_SMBUS_BYTE;
>
> data.byte = 8;
> arg.data = &data;
>
> char buf[2] = {0x79, 0x92};
> write(file, buf,2);
> int i;
> for(i = 0; i < 20; i++)
> {
> read(file,buf,2);
>
> unsigned int a =0;
> a = (buf[0] & 0xF) << 8 | buf[1] ;
> printf("reading %u\n",a);
>
> sleep(1);
> }
>
> }
>
> No idea why I did it without using the smbus_write commands
> though. The iio driver is i2c_transfers I'm afraid.
>
> as for i2c detect, I've just blugeoned it into building for
> the pxa271 board I'm using and it picks up a max1239 just fine.
can i access the ringbuffer of this driver via sysfs or how userspace side
should work?
Regards
Andreas
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