C8051F300 Datasheet, PDF (43/176 Pages) List of Unclassifed Manufacturers – Mixed Signal ISP Flash MCU Family

C8051F300/1/2/3/4/5
5.4. Programmable Window Detector
The ADC Programmable Window Detector continuously compares the ADC0 output to user-programmed
limits, and notifies the system when a desired condition is detected. This is especially effective in an inter-
rupt-driven system, saving code space and CPU bandwidth while delivering faster system response times.
The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used in polled mode. The
ADC0 Greater-Than (ADC0GT) and Less-Than (ADC0LT) registers hold the comparison values. Example
comparisons for Single-ended and Differential modes are shown in Figure 5.6 and Figure 5.7, respectively.
Notice that the window detector flag can be programmed to indicate when measured data is inside or out-
side of the user-programmed limits depending on the contents of the ADC0LT and ADC0GT registers.
5.4.1. Window Detector In Single-Ended Mode
Figure 5.6 shows two example window comparisons for Single-ended mode, with ADC0LT = 0x20 and
ADC0GT = 0x10. Notice that in Single-ended mode, the codes vary from 0 to VREF x (255/256) and are
represented as 8-bit unsigned integers. In the left example, an AD0WINT interrupt will be generated if the
ADC0 conversion word (ADC0) is within the range defined by ADC0GT and ADC0LT
(if 0x10 < ADC0 < 0x20). In the right example, and AD0WINT interrupt will be generated if ADC0 is outside
of the range defined by ADC0GT and ADC0LT (if ADC0 < 0x10 or ADC0 > 0x20).
Input Voltage
(P0.x - GND)
REF x (255/256)
ADC0
0xFF
REF x (32/256)
REF x (16/256)
0x21
0x20
0x1F
0x11
0x10
0x0F
AD0WINT
not affected
Input Voltage
(P0.x - GND)
REF x (255/256)
ADC0LT
AD0WINT=1
ADC0GT
REF x (32/256)
REF x (16/256)
ADC0
0xFF
0x21
0x20
0x1F
0x11
0x10
0x0F
AD0WINT=1
ADC0GT
AD0WINT
not affected
ADC0LT
0
0x00
AD0WINT
not affected
0
0x00
AD0WINT=1
Figure 5.6. ADC Window Compare Examples, Single-Ended Mode
Rev. 2.8
43