C8051F320/1

58 Rev. 1.4

Comparator outputs can be polled in software, used as an interrupt source, and/or routed to a Port pin.

When routed to a Port pin, Comparator outputs are available asynchronous or synchronous to the system

clock; the asynchronous output is available even in STOP mode (with no system clock active). When dis

abled, the Comparator output (if assigned to a Port I/O pin via the Cr

ossbar) defaults to the logic low state,

and supply current falls to less than 100 nA. See Section “14.1. Priority Crossbar Decoder” on page 128

for details on configuring Comparator outputs via the digita

l Crossbar. Comparator inputs can be externally

driven from –0.25 V to (V

) + 0.25 V without damage or upset. The complete Comparator electrical spec-

ifications are given in Table 7.1.

Comparator response time may be configured in software via the CPTnMD registers (see Figure 7.3 and

Figure 7.6). Selecting a longer response time reduces the Comparator supply current. See Table 7.1 for

complete timing and supply current specifications.

VDD

CPT1CN

Crossbar

Interrupt

Logic

SET

CLR

SET

CLR

(SYNCHRONIZER)

GND

CP1 +

P1.2

P1.6

P2.2

P2.6

CP1 -

P1.3

P1.7

P2.3

P2.7

CP1EN

CP1OUT

CP1RIF

CP1FIF

CP1HYP1

CP1HYP0

CP1HYN1

CP1HYN0

CPT1MX

CMX1N1

CMX1N0

CMX1P1

CMX1P0

CPT1MD

CP1RIE

CP1FIE

CP1MD1

CP1MD0

CP1

CP1A

CP1

Rising-edge

CP1

Falling-edge

CP1

Interrupt

CP1RIE

CP1FIE

Note: P2.6 and P2.7 available

only on C8051F320

Figure 7.2. Comparator1 Functional Block Diagram

Positive Hysteresis Voltage

(Programmed with CP0HYP Bits)

Negative Hysteresis Voltage

(Programmed by CP0HYN Bits)

VIN-

VIN+

INPUTS

CIRCUIT CONFIGURATION

CP0+

CP0-

CP0

VIN+

VIN-

OUT

Positive Hysteresis

Disabled

Maximum

Positive Hysteresis

Negative Hysteresis

Disabled

Maximum

Negative Hysteresis

OUTPUT

Comparator hysteresis is programmed using Bits3–0 in the Comparator Control Register CPTnCN (shown

in Figure 7.1 and Figure 7.4). The amount of negative hysteresis volta

ge is determined by the settings of

the CPnHYN bits. As shown in Figure 7.3, settings of 20, 10 or 5 mV of negative hysteresis can be

programmed, or negative hysteresis can be disabled. In a similar

way, the amount of positive hysteresis is

determined by the setting the CPnHYP bits.

Comparator interrupts can be generated on

both

rising-edge and falling-edge output transitions. (For Inter-

rupt enable and priority control, see Section “9.3. Interrupt Handler” on page 87.) The CPnFIF flag is set to

‘1’ upon a Comparator falling-edge, and the CPnRIF flag

is set to ‘1’ upon the Comparator rising-edge.

Once set, these bits remain set until cleared by software. The output state of the Comparator can be

obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to

‘1’, and is disabled by clearing this bit to ‘0’.

Rev. 1.4 59

C8051F320/1

Figure 7.3. Comparator Hysteresis Plot

C8051F320/1

60 Rev. 1.4

SFR Definition 7.1. CPT0CN: Comparator0 Control

Bit7: CP0EN: Comparator0 Enable Bit.

0: Comparator0 Disabled.

1: Comparator0 Enabled.

Bit6: CP0OUT: Comparator0 Output State Flag.

0: Voltage on CP0+ < CP0–.

1: Voltage on CP0+ > CP0–.

Bit5: CP0RIF: Comparator0 Rising-Edge Flag.

0: No Comparator0 Rising Edge has occurred since this flag was last cleared.

1: Comparator0 Rising Edge has occurred.

Bit4: CP0FIF: Comparator0 Falling-Edge Flag.

0: No Comparator0 Falling-Edge has occurred since this flag was last cleared.

1: Comparator0 Falling-Edge Interrupt has occurred.

Bits3–2: CP0HYP1–0: Comparator0 Positive Hysteresis Control Bits.

00: Positive Hysteresis Disabled.

01: Positive Hysteresis = 5 mV.

10: Positive Hysteresis = 10 mV.

11: Positive Hysteresis = 20 mV.

Bits1–0: CP0HYN1–0: Comparator0 Negative Hysteresis Control Bits.

00: Negative Hysteresis Disabled.

01: Negative Hysteresis = 5 mV.

10: Negative Hysteresis = 10 mV.

11: Negative Hysteresis = 20 mV.

R/W R R/W R/W R/W R/W R/W R/W Reset Value

CP0EN CP0OUT CP0RIF CP0FIF CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000

Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:

0x9B

Part #	C8051F321-GMR
Description	16KB,10ADC,USB,28PIN MCU (LEAD FREE) MLP28 -40 TO 85 DEG.
Category	IC
Availability	In Stock
Qty	560

Qty	Price
1 - 24	$10.41286
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276 +	$6.46859

C8051F321-GMR

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Technical Document