C8051F850-B-GM Datasheet, PDF (84/290 Pages) Silicon Laboratories – Low-Cost 8-bit MCU Family with up to 8 kB of Flash

C8051F85x/86x
Input Voltage
V_REF x 1023/1024
V_REF x 512/1024
V_REF x 511/1024
0
Repeat Count = 4
Shift Right = 1
11-Bit Result
0x07F7
0x0400
0x03FE
0x0000
Repeat Count = 16
Shift Right = 2
12-Bit Result
0x0FFC
0x0800
0x04FC
0x0000
Repeat Count = 64
Shift Right = 3
13-Bit Result
0x1FF8
0x1000
0x0FF8
0x0000
14.7. Programmable Window Detector
The ADC Programmable Window Detector continuously compares the ADC0 output registers to user-programmed
limits, and notifies the system when a desired condition is detected. This is especially effective in an interrupt-
driven system, saving code space and CPU bandwidth while delivering faster system response times. The window
detector interrupt flag (ADWINT in register ADC0CN0) can also be used in polled mode. The ADC0 Greater-Than
(ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL) registers hold the comparison values. The window
detector flag can be programmed to indicate when measured data is inside or outside of the user-programmed
limits, depending on the contents of the ADC0 Less-Than and ADC0 Greater-Than registers.
14.7.1. Window Detector In Single-Ended Mode
Figure 14.6 shows two example window comparisons for right-justified data, with ADC0LTH:ADC0LTL = 0x0080
(128d) and ADC0GTH:ADC0GTL = 0x0040 (64d). The input voltage can range from 0 to VREF x (1023/1024) with
respect to GND, and is represented by a 10-bit unsigned integer value. In the left example, an ADWINT interrupt
will be generated if the ADC0 conversion word (ADC0H:ADC0L) is within the range defined by
ADC0GTH:ADC0GTL and ADC0LTH:ADC0LTL (if 0x0040 < ADC0H:ADC0L < 0x0080). In the right example, and
ADWINT interrupt will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT
and ADC0LT registers (if ADC0H:ADC0L < 0x0040 or ADC0H:ADC0L > 0x0080). Figure 14.7 shows an example
using left-justified data with the same comparison values.
Input Voltage
(Px.x - GND)
VREF x (1023/
1024)
ADC0H:ADC0L
0x03FF
VREF x (128/1024)
VREF x (64/1024)
0x0081
0x0080
0x007F
0x0041
0x0040
0x003F
ADWINT
not affected
ADC0LTH:ADC0LTL
ADWINT=1
ADC0GTH:ADC0GTL
Input Voltage
(Px.x - GND)
VREF x (1023/
1024)
ADC0H:ADC0L
0x03FF
VREF x (128/1024)
VREF x (64/1024)
0x0081
0x0080
0x007F
0x0041
0x0040
0x003F
ADWINT=1
ADC0GTH:ADC0GTL
ADWINT
not affected
ADC0LTH:ADC0LTL
ADWINT
not affected
ADWINT=1
0
0x0000
0
0x0000
Figure 14.6. ADC Window Compare Example: Right-Justified Single-Ended Data
Preliminary Rev 0.6
87