Processor Expert SoftwareのトピックRe: PEx I2C Target Slave Address Init Error ?

PEx I2C Target Slave Address Init Error ?

Designer11 — Wed, 08 Mar 2017 03:21:45 GMT

Hi Everyone,

When using Processor Expert to assign an I2C slave address, 0xA0 it keeps saying "This value is greater 127, although 7-bit addressing is used". In the past, i never had this issue when i bit bang the I2C. Is this a bug in Processor Expert ?

The processor i'm using is K64F. Will i face the same I2C issue if i use the KDSK ?

The slave address is 0xA0

Thanks.

Re: PEx I2C Target Slave Address Init Error ?

Jorge_Gonzalez — Wed, 08 Mar 2017 04:10:14 GMT

Hello Vu Nguyen,

This is not a bug. 0xA0 is an 8-bit value (10100000b), so not valid for a 7-bit slave address. As noted by PE the max address would be 127 (1111111b).

I believe you are taking the R/W bit as part of the address. See the 7-bit slave addressing scheme below:

If that is the case then take only the 7 most significant bits to form the slave address. For 0xA0 (10100000b) the actual slave address would be 0x50 (1010000b).

Best Regards!

Jorge Gonzalez

Re: PEx I2C Target Slave Address Init Error ?

Designer11 — Wed, 08 Mar 2017 04:57:15 GMT

Hi Jorge,

Thanks! Your answer makes sense. I got it now.

Thanks,