Posted on May 07, 2007 at 07:52While planning to use the input capture feature of ST7LiteUSx, I found the following error.
The ST7LiteUSx Rev.4 datasheet issued on January 2007 at page 48 says:
Quote:
After a MCU reset, it starts incrementing from 0 at a frequency of fosc. A counter overflow events occurs when the counter rolls over from 1F39h to 00h. If fosc = 8 MHz, then the time period between two counter overflows events is 1ms
The rollover value is wrong. If fosc = 8 MHz, 8000 clock pulses are needed to make a ms. Since 8000 = 1F40h, the rollover value should be 1F3Fh not 1F39h.
If the LITE TIMER is shared between the ST7FLITE family, the other datasheets can confirm the error.
For instance, the ST7LITE3x Rev. 7 datasheet issued on December 2006 at page 72 says:
Quote:
After a MCU reset, it starts incrementing from 0 at a frequency of fosc/32. A counter overflow events occurs when the counter rolls over from F9h to 00h. If fosc = 8 MHz, then the time period between two counter overflows events is 1ms
The ST7FLITE3x LITE TIMER is an 8 bit counter driven by a frequency divider whose output is fosc/32. Since 32 = 2^5, and 8 + 5 = 13, the two LITE TIMERS seem to be the same.
If it is true, can I use the ST7LiteUSx LTIC value as I use the ST7FLITE3x LTIC?
Why have a different description for the same thing?
EtaPhi
