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COP8AME9EMW8 参数 Datasheet PDF下载

COP8AME9EMW8图片预览
型号: COP8AME9EMW8
PDF下载: 下载PDF文件 查看货源
内容描述: 8位CMOS闪存微控制器,具有8K内存,双通道运算放大器,虚拟EEROM ,温度传感器, 10位A / D和掉电复位 [8-Bit CMOS Flash Microcontroller with 8k Memory, Dual Op Amps, Virtual EEROM, Temperature Sensor,10-Bit A/D and Brownout Reset]
分类和应用: 闪存传感器温度传感器微控制器和处理器外围集成电路运算放大器光电二极管时钟
文件页数/大小: 83 页 / 908 K
品牌: NSC [ National Semiconductor ]
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12.0 Timers (Continued)  
12.1.1 ITMR Register  
HSTCR  
Bit  
1
Bit  
0
Bit 7  
Bit 6  
Bit 5  
Bit 4  
Bit 3  
Bit 2  
T2IDLE  
0
0
0
0
0
T3HS T2HS  
CCK  
LSON HSON DCEN  
RSVD ITSEL2 ITSEL1 ITSEL0  
Bit 3 Bit 2 Bit 1 Bit 0  
SEL  
Bit 7  
Bit 6  
Bit 5  
Bit 4  
12.2.2 Mode 1. Processor Independent PWM Mode  
One of the timer’s operating modes is the Processor Inde-  
pendent PWM mode. In this mode, the timers generate a  
“Processor Independent” PWM signal because once the  
timer is set up, no more action is required from the CPU  
which translates to lower software overhead and greater  
throughput. The user software services the timer block only  
when the PWM parameters require updating. This capability  
is provided by the fact that the timer has two separate 16-bit  
reload registers. One of the reload registers contains the  
“ON” time while the other holds the “OFF” time. By contrast,  
a microcontroller that has only a single reload register re-  
quires an additional software to update the reload value  
(alternate between the on-time/off-time).  
Bits 7–4: Described in Section 13.0 Power Saving  
Features.  
Note: Documentation for previous COP8 devices, which in-  
cluded the Programmable Idle Timer, recommended the user  
write zero to the high order bits of the ITMR Register. If  
existing programs are updated to use this device, writing  
zero to these bits will cause the device to reset (see Section  
13.0 Power Saving Features).  
RSVD: This bit is reserved and must be set to 0.  
ITSEL2:0: Selects the Idle Timer period as described in  
Table 14, Idle Timer Window Length.  
Any time the IDLE Timer period is changed there is the  
possibility of generating a spurious IDLE Timer interrupt by  
setting the T0PND bit. The user is advised to disable IDLE  
Timer interrupts prior to changing the value of the ITSEL bits  
of the ITMR Register and then clear the T0PND bit before  
attempting to synchronize operation to the IDLE Timer.  
The timer can generate the PWM output with the width and  
duty cycle controlled by the values stored in the reload  
registers. The reload registers control the countdown values  
and the reload values are automatically written into the timer  
when it counts down through 0, generating interrupt on each  
reload. Under software control and with minimal overhead,  
the PWM outputs are useful in controlling motors, triacs, the  
intensity of displays, and in providing inputs for data acqui-  
sition and sine wave generators.  
12.2 TIMER T1, TIMER T2, AND TIMER T3  
The device has a set of three powerful timer/counter blocks,  
T1, T2, and T3. Since T1, T2 and T3 are identical, except for  
the high speed operation of T2 and T3, all comments are  
equally applicable to any of the three timer blocks which will  
be referred to as Tx. Differences between the timers will be  
specifically noted.  
In this mode, the timer Tx counts down at a fixed rate of tC  
(T2 and T3 may be selected to operate from MCLK). Upon  
every underflow the timer is alternately reloaded with the  
contents of supporting registers, RxA and RxB. The very first  
underflow of the timer causes the timer to reload from the  
register RxA. Subsequent underflows cause the timer to be  
reloaded from the registers alternately beginning with the  
register RxB.  
The core 16-bit timer is designated T1, this section uses Tx  
to refer to timer T1 and all additional timers that operate in  
exactly the same manner as timer T1, with the exception of  
the high speed capability described later.  
Each timer block consists of a 16-bit timer, Tx, and two  
supporting 16-bit autoreload/capture registers, RxA and  
RxB. Each timer block has two pins associated with it, TxA  
and TxB. The pin TxA supports I/O required by the timer  
block, while the pin TxB is an input to the timer block. The  
timer block has three operating modes: Processor Indepen-  
dent PWM mode, External Event Counter mode, and Input  
Capture mode.  
Figure 15 shows a block diagram of the timer in PWM mode.  
The underflows can be programmed to toggle the TxA output  
pin. The underflows can also be programmed to generate  
interrupts.  
Underflows from the timer are alternately latched into two  
pending flags, TxPNDA and TxPNDB. The user must reset  
these pending flags under software control. Two control  
enable flags, TxENA and TxENB, allow the interrupts from  
the timer underflow to be enabled or disabled. Setting the  
timer enable flag TxENA will cause an interrupt when a timer  
underflow causes the RxA register to be reloaded into the  
timer. Setting the timer enable flag TxENB will cause an  
interrupt when a timer underflow causes the RxB register to  
be reloaded into the timer. Resetting the timer enable flags  
will disable the associated interrupts.  
The control bits TxC3, TxC2, and TxC1 allow selection of the  
different modes of operation.  
12.2.1 Timer Operating Speeds  
Each of the Tx timers, except T1, have the ability to operate  
at either the instruction cycle frequency (low speed) or the  
internal clock frequency (MCLK). For 10 MHz CKI, the in-  
struction cycle frequency is 2 MHz and the internal clock  
frequency is 20 MHz. This feature is controlled by the High  
Speed Timer Control Register, HSTCR. Its format is shown  
below. To place a timer, Tx, in high speed mode, set the  
appropriate TxHS bit to 1. For low speed operation, clear the  
appropriate TxHS bit to 0. This register is cleared to 00 on  
Reset.  
Either or both of the timer underflow interrupts may be  
enabled. This gives the user the flexibility of interrupting  
once per PWM period on either the rising or falling edge of  
the PWM output. Alternatively, the user may choose to inter-  
rupt on both edges of the PWM output.  
The T2IDLE bit is used to allow T2 operation while the  
device is in Idle mode. See Section 12.4 TIMER T2 OPERA-  
TION IN IDLE MODE for further information.  
31  
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