Datasheet

DocID8349 Rev 7 165/170
ST7LITE20F2 ST7LITE25F2 ST7LITE29F2 Important notes
169
16 Important notes
16.1 Execution of BTJX instruction
When testing the address $FF with the "BTJT" or "BTJF" instructions, the CPU may perform
an incorrect operation when the relative jump is negative and performs an address page
change.
To avoid this issue, including when using a C compiler, it is recommended to never use
address $00FF as a variable (using the linker parameter for example).
16.2 ADC conversion spurious results
Spurious conversions occur with a rate lower than 50 per million. Such conversions happen
when the measured voltage is just between 2 consecutive digital values.
Workaround
A software filter should be implemented to remove erratic conversion results whenever they
may cause unwanted consequences.
16.3 A/D converter accuracy for first conversion
When the ADC is enabled after being powered down (for example when waking up from
HALT, ACTIVE-HALT or setting the ADON bit in the ADCCSR register), the first conversion
(8-bit or 10-bit) accuracy does not meet the accuracy specified in the datasheet.
Workaround
In order to have the accuracy specified in the datasheet, the first conversion after a ADC
switch-on has to be ignored.
16.4 Negative injection impact on ADC accuracy
Injecting a negative current on an analog input pins significantly reduces the accuracy of the
AD Converter. Whenever necessary, the negative injection should be prevented by the
addition of a Schottky diode between the concerned I/Os and ground.
Injecting a negative current on digital input pins degrades ADC accuracy especially if
performed on a pin close to ADC channel in use.
16.5 Clearing active interrupts outside interrupt routine
When an active interrupt request occurs at the same time as the related flag or interrupt
mask is being cleared, the CC register may be corrupted.