XE8805 SEMTECH [Semtech Corporation], XE8805 Datasheet - Page 49
XE8805
Manufacturer Part Number
XE8805
Description
Data Acquisition MCU
Manufacturer
SEMTECH [Semtech Corporation]
Datasheet
1.XE8805.pdf
(156 pages)
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
XE8805AMI028LF
Manufacturer:
SEMTECH/美国升特
Quantity:
20 000
- Current page: 49 of 156
- Download datasheet (2Mb)
7.6 Clock source selection
There are three possible clock sources available for the CPU clock. The RC clock is always selected after power-
up or after Sleep mode. The CPU clock selection is done with the bit CpuSel in RegSysClock (0= RC clock, 1= 32
kHz from Xtal if EnableXtal =1, ExtClk = 0 and EnExtClk = 0 else external clock).
Switching from one clock source to another is glitch free.
The next table summarizes the different clock configurations of the circuit:
Note 1: The CPU clock can be divided by using the freq instruction (see coolrisc instruction set)
Switching from one clock source to another and stopping the unused clock source must be performed using 3
MOVE instructions to RegSysClock. First select the new clock source, secondly change the CpuSel bit and finally
stop the unused one.
7.7 RegSysMisc Description
The RCOnPA0 bit in RegSysMisc can be used to enable the RC oscillator on an event external to the circuit. If
RCOnPA0 is 1, the RC oscillator is enabled (EnableRC bit is set to 1) as soon as the value on port A pin PA[0] is
equal to 1. The port A pin can be debounced (see port A documentation).
Bit OutputCkXtal allows to show the Xtal clock on PB[3]. The EnableXtal bit must be set to 1 else PB[3] equals 0
(see port B documentation to set up the port B).
Bit OutputCpuCk allows to show the CpuClock on PB[2] (see port B documentation).
© Semtech 2006
Bit DebFast in the RegSysMisc register allows to chose the debouncer clock between 256Hz and 8kHz (DebFast
= 0 and DebFast = 1 respectively). The Debouncer clock is used to debounce PA inputs (see port A
documentation).
Mode
name
Sleep
Xtal
RC
RC + Xtal
External
RC
External
Clock Sources
+
0
0
0
0
1
1
0
0
1
1
0
1
Table 7-12: Table of clocking modes.
X
X
0
1
0
1
CpuSel=0
RC
RC
RC
Off
Off
Off
7-8
Cpuck
Note 1
CpuSel=1
External
External
Xtal
Xtal
RC
Off
Clock targets
Prescaler
Clock
input
High
RC
RC
RC
Off
Off
Off
High presc.
High presc.
Prescaler
XE8805/05A
Clock
input
Low
Xtal
Xtal
Off
Off
www.semtech.com
Related parts for XE8805
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
Part Number:
Description:
HIGH VOLTAGE CAPACITORS MONOLITHIC CERAMIC TYPE
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
EZ1084CM5.0 AMP POSITIVE VOLTAGE REGULATOR
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
3.0 AMP LOW DROPOUT POSITIVE VOLTAGE REGULATORS
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
RailClamp Low Capacitance TVS Diode Array
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Semtech Corporation
Datasheet:
Part Number:
Description:
Manufacturer:
Semtech Corporation
Datasheet: