參數(shù)資料
型號(hào)： TMS320LC542-40
元件分類： 數(shù)字信號(hào)處理
英文描述： Digital Signal Processor
中文描述： 數(shù)字信號(hào)處理器
文件頁(yè)數(shù)： 34/111頁(yè)
文件大小： 1426K
代理商： TMS320LC542-40
TMS320C54x, TMS320LC54x, TMS320VC54x
FIXED-POINT DIGITAL SIGNAL PROCESSORS
SPRS039C – FEBRUARY 1996 – REVISED DECEMBER 1999
34
POST OFFICE BOX 1443
HOUSTON, TEXAS 77251–1443
software-programmable PLL (’545A, ’546A, ’548, and ’549) (continued)
Immediately following reset, the clock mode is determined by the values of the three external pins: CLKMD1,
CLKMD2, and CLKMD3. The modes corresponding to the CLKMD pins are shown in Table 6.
Table 6. Clock Mode Settings at Reset
CLKMD1
CLKMD2
CLKMD3
CLKMD REGISTER
RESET VALUE
CLOCK MODE
0
0
0
0000h
Divide-by-two, with external source
0
0
1
1000h
Divide-by-two, with external source
0
1
0
2000h
Divide-by-two, with external source
1
0
0
4000h
Divide-by-two, internal oscillator enabled
1
1
0
6000h
Divide-by-two, with external source
Divide-by-two, internal oscillator enabled
PLL
×
1 with external source
Stop mode
1
1
1
7000h
1
0
1
0007h
0
1
1
—
Reserved mode (’549 only). Do not use in normal operation.
Following reset, the software-programmable PLL can be programmed to any configuration desired, as
described above. Note that when the PLL
×
1 with external source option (CLKMD[1–3]=101) is selected during
reset, the internal PLL lock-count timer is not active; therefore, the system must delay releasing reset in order
to allow for the PLL lock-time delay. Also, note that both the hardware- and the software-programmable PLLs
require the device to be reset after power up to begin functioning properly.
programming considerations when using the software-programmable PLL
The software-programmable PLL offers many different options in startup configurations, operating modes, and
power-saving features. Programming considerations and several software examples are presented here to
illustrate the proper use of the software-programmable PLL at start-up, when switching between different
clocking modes, and before and after IDLE1/IDLE2/IDLE3 instruction execution.
use of the PLLCOUNT programmable lock timer
During the lockup period, the PLL should not be used to clock the ’54x. The PLLCOUNT programmable lock
timer provides a convenient method of automatically delaying clocking of the device by the PLL until lock is
achieved.
The PLL lock timer is a counter, loaded from the PLLCOUNT field in the CLKMD register, that decrements from
its preset value to 0. The timer can be preset to any value from 0 to 255, and its input clock is CLKIN divided
by 16. The resulting lockup delay can therefore be set from 0 to 255
16 CLKIN cycles.
The lock timer is activated when the clock generator operating mode is switched from DIV to PLL (see the
section describing switching from DIV mode to PLL mode). During the lockup period, the clock generator
continues to operate in DIV mode; after the PLL lock timer has decremented to zero, the PLL begins clocking
the ’54x.
Accordingly, the value loaded into PLLCOUNT is chosen based on the following relationship:
PLLCOUNT > Lockup Time / (16
t
CLKIN
)
where t
CLKIN
is the input reference clock period and lockup time is the required PLL lockup time as shown in
Figure 8.
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TMS320LC542PBK2-50 功能描述:數(shù)字信號(hào)處理器和控制器 - DSP, DSC Dig Signal Proc RoHS:否 制造商:Microchip Technology 核心:dsPIC 數(shù)據(jù)總線寬度:16 bit 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:2 KB 最大時(shí)鐘頻率:40 MHz 可編程輸入/輸出端數(shù)量:35 定時(shí)器數(shù)量:3 設(shè)備每秒兆指令數(shù):50 MIPs 工作電源電壓:3.3 V 最大工作溫度:+ 85 C 封裝 / 箱體:TQFP-44 安裝風(fēng)格:SMD/SMT
TMS320LC542PGE1-40 功能描述:數(shù)字信號(hào)處理器和控制器 - DSP, DSC Dig Signal Proc RoHS:否 制造商:Microchip Technology 核心:dsPIC 數(shù)據(jù)總線寬度:16 bit 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:2 KB 最大時(shí)鐘頻率:40 MHz 可編程輸入/輸出端數(shù)量:35 定時(shí)器數(shù)量:3 設(shè)備每秒兆指令數(shù):50 MIPs 工作電源電壓:3.3 V 最大工作溫度:+ 85 C 封裝 / 箱體:TQFP-44 安裝風(fēng)格:SMD/SMT
TMS320LC542PGE1-50 功能描述:數(shù)字信號(hào)處理器和控制器 - DSP, DSC Dig Signal Proc RoHS:否 制造商:Microchip Technology 核心:dsPIC 數(shù)據(jù)總線寬度:16 bit 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:2 KB 最大時(shí)鐘頻率:40 MHz 可編程輸入/輸出端數(shù)量:35 定時(shí)器數(shù)量:3 設(shè)備每秒兆指令數(shù):50 MIPs 工作電源電壓:3.3 V 最大工作溫度:+ 85 C 封裝 / 箱體:TQFP-44 安裝風(fēng)格:SMD/SMT
TMS320LC542PGE2-40 功能描述:數(shù)字信號(hào)處理器和控制器 - DSP, DSC Dig Signal Proc RoHS:否 制造商:Microchip Technology 核心:dsPIC 數(shù)據(jù)總線寬度:16 bit 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:2 KB 最大時(shí)鐘頻率:40 MHz 可編程輸入/輸出端數(shù)量:35 定時(shí)器數(shù)量:3 設(shè)備每秒兆指令數(shù):50 MIPs 工作電源電壓:3.3 V 最大工作溫度:+ 85 C 封裝 / 箱體:TQFP-44 安裝風(fēng)格:SMD/SMT
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