298
CHAPTER 18 8/10-BIT A/D CONVERTER
18.6.2
A/D conversion data protection function
When A/D conversion is performed in the interrupt enabled state, the conversion data
protection function operates.
■
A/D Conversion Data Protection Function
The A/D converter has just one data register that holds conversion data. When a single A/D conversion is
completed, the data in the data register is rewritten.
If the conversion data were not transferred to memory before the next conversion data was stored, part of
the conversion data would be lost. The data protection function operates in the interrupt enabled state
(INTE = 1), as described below, to prevent loss of data.
●
Data protection function when EI
2
OS is not used
When conversion data is stored in the A/D data register (ADCR), the INT bit of the A/D control status
register1 (ADCS1) is set to "1".
While the INT bit is "1", A/D conversion is halted.
Halt status is released when the INT bit is cleared after data in the A/D data register (ADCR) has been
transferred to memory by the interrupt routine.
●
Data protection function when EI
2
OS is used
In continuous conversion using EI
2
OS, the PAUS bit of the A/D control status register1 (ADCS1) is kept at
"1" when a conversion ends. This status continues until EI
2
OS finishes transferring the conversion data
from the data register to memory. In the meantime, the A/D conversion is halted, and the next conversion
data is not stored. When the data transfer to memory is completed, conversion resumes, but once PAUS bit
is set, it is not cleared by itself, write "0" to clear PAUS bit.
Figure 18.6-3 shows operation flowchart of the data protection function when EI
2
OS is used.
Summary of Contents for MB90390 Series
Page 2: ......
Page 4: ......
Page 17: ...xiii APPENDIX D List of Interrupt Vectors 690 INDEX 695 ...
Page 18: ...xiv ...
Page 132: ...104 CHAPTER 5 CLOCKS ...
Page 152: ...124 CHAPTER 6 CLOCK MODULATOR ...
Page 210: ...182 CHAPTER 11 TIME BASE TIMER ...
Page 218: ...190 CHAPTER 12 WATCHDOG TIMER ...
Page 264: ...236 CHAPTER 14 16 BIT RELOAD TIMER WITH EVENT COUNT FUNCTION ...
Page 274: ...246 CHAPTER 15 WATCH TIMER ...
Page 306: ...278 CHAPTER 17 DTP EXTERNAL INTERRUPTS ...
Page 338: ...310 CHAPTER 18 8 10 BIT A D CONVERTER ...
Page 364: ...336 CHAPTER 19 UART0 UART1 ...
Page 398: ...370 CHAPTER 20 UART2 UART3 Figure 20 5 2 ORE Set Timing Receive data RDRF ORE ...
Page 432: ...404 CHAPTER 20 UART2 UART3 ...
Page 482: ...454 CHAPTER 22 SERIAL I O ...
Page 560: ...532 CHAPTER 24 STEPPING MOTOR CONTROLLER ...
Page 582: ...554 CHAPTER 27 ROM MIRRORING MODULE ...
Page 632: ...604 CHAPTER 29 EXAMPLES OF SERIAL PROGRAMMING CONNECTION ...
Page 722: ...694 APPENDIX ...
Page 723: ...695 INDEX The index follows on the next page This is listed in alphabetic order ...
Page 740: ......