XE8806ARI000 View Datasheet(PDF) - Semtech Corporation

Part Name

Description

Manufacturer

XE8806ARI000

Ultra Low-Power Low-Voltage Radio Machines

Semtech Corporation 

XE8806A/XE8807A

The external clock sources can be debounced or not by properly setting the PortA configuration registers.

Additionally, the external clock sources can be divided by two in the counter block, thus enabling higher external

clock frequencies, by setting the CntXExtDiv bits in the RegCntOn register.

Switching between an internal and an external clock source can only be performed while the counter is stopped.

The enabling or disabling of the external clock frequency division can only be performed while the counter using

this clock is stopped, or when this counter is running on an internal clock source.

17.8 Counter mode selection

Each counter can work in one of the following modes:

1) Counter, downcount & upcount

2) Captured counter, downcount & upcount (only counters A&B)

3) PWM, downcount & upcount

4) Captured PWM, downcount and upcount

The counters A and B or C and D can be cascaded or not. In cascaded mode, A and C are the LSB counters while

B and D are the MSB counters.

Table 17-12 shows the different operation modes of the counters A and B as a function of the mode control bits.

For all counter modes, the source of the down or upcount selection is given (either the bit CntADownUp or the bit

CntBDownUp). Also, the mapping of the interrupt sources IrqA and IrqB and the PWM output on PB(0) in these

different modes is shown.

CascadeAB

CountPWM0

CapFunc(1:0)

0

0

00

1

0

00

0

1

00

1

1

00

1x

0

0

or

x1

1x

1

0

or

x1

1x

0

1

or

x1

1

1x

1

or

x1

Counter A Counter B

mode

mode

Counter 8b Counter 8b

Downup: A Downup: B

Counter 16b AB

Downup: A

PWM 8b Counter 8b

Downup: A Downup: B

PWM 10 – 16b AB

Downup A

Captured Captured

counter 8b counter 8b

Downup: A Downup: B

Captured counter 16b AB

Downup: A

Captured Captured

PWM 8b counter 8b

Downup: A Downup: B

Captured 10 – 16b PWM

(captured value on 16b)

Downup: A

IrqA

source

Counter

A

Counter

AB

-

-

Capture

A

Capture

AB

Capture

A

Capture

AB

IrqB

source

Counter

B

-

Counter

B

-

Capture

B

Capture

AB

Capture

B

Capture

AB

Table 17-12: Operating modes of the counters A and B

PB(0)

function

PB(0)

PB(0)

PWM A

PWM AB

PB(0)

PB(0)

PWM A

PWM AB

Table 17-13 shows the different operation modes of the counters C and D as a function of the mode control bits.

For all counter modes, the source of the down or upcount selection is given (either the bit CntCDownUp or the bit

CntDDownUp). The mapping of the interrupt sources IrqC and IrqD and the PWM output on PB(1) in these

different modes is also shown.

The switching between different modes must be done while the concerned counters are stopped. While switching

capture mode on and off, unwanted interrupts can appear on the interrupt channels concerned by this mode

change.

© Semtech 2006

17-6

www.semtech.com

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