参数资料
型号: XE8805AMI028LF
厂商: Semtech
文件页数: 101/156页
文件大小: 0K
描述: IC DAS 16BIT FLASH 8K MTP 64LQFP
标准包装: 160
系列: XE880x
应用: 感测机
核心处理器: Coolrisc816?
程序存储器类型: 闪存(22 kB)
控制器系列: XE8000
RAM 容量: 512 x 8
接口: UART,USRT
输入/输出数: 24
电源电压: 2.4 V ~ 5.5 V
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 64-LQFP
包装: 托盘
供应商设备封装: 64-LQFP(10x10)
产品目录页面: 585 (CN2011-ZH PDF)
配用: XE8000MP-ND - PROG BOARD AND PROSTART2 CARD
Semtech 2006
www.semtech.com
7-8
XE8805/05A
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:
Clock Sources
Clock targets
Cpuck
Note 1
Mode
name
En
E
x
tC
lk
EnableRc
EnableXtal
CpuSel=0
CpuSel=1
High
Prescaler
Clock
input
Low
Prescaler
Clock
input
Sleep
0
Off
Xtal
0
1
Off
Xtal
Off
Xtal
RC
0
1
0
RC
High presc.
RC + Xtal
0
1
RC
Xtal
RC
Xtal
External
1
0
X
Off
External
Off
RC
+
External
1
X
RC
External
RC
High presc.
Table 7-12: Table of clocking modes.
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 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).
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).
Not
Recommended
for
New
Designs
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