参数资料
型号: ST72621L4T1
厂商: STMICROELECTRONICS
元件分类: 微控制器/微处理器
英文描述: 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PQFP44
封装: TQFP-44
文件页数: 82/134页
文件大小: 815K
代理商: ST72621L4T1
ST7262
51/134
10.3 TIMEBASE UNIT (TBU)
10.3.1 Introduction
The Timebase unit (TBU) can be used to generate
periodic interrupts.
10.3.2 Main Features
s
8-bit upcounter
s
Programmable prescaler
s
Period between interrupts: max. 8.1ms (at 8
MHz fCPU )
s
Maskable interrupt
s
Cascadable with PWM/ART TImer
10.3.3 Functional Description
The TBU operates as a free-running upcounter.
When the TCEN bit in the TBUCSR register is set
by software, counting starts at the current value of
the TBUCV register. The TBUCV register is incre-
mented at the clock rate output from the prescaler
selected by programming the PR[2:0] bits in the
TBUCSR register.
When the counter rolls over from FFh to 00h, the
OVF bit is set and an interrupt request is generat-
ed if ITE is set.
The user can write a value at any time in the
TBUCV register.
If the cascading option is selected (CAS bit=1 in
the TBUCSR register), the TBU and the the ART
TImer counters act together as a 16-bit counter. In
this case, the TBUCV register is the high order
byte, the ART counter (ARTCAR register) is the
low order byte. Counting is clocked by the ART
timer clock (Refer to the description of the ART
Timer ARTCSR register).
10.3.4 Programming Example
In this example, timer is required to generate an in-
terrupt after a delay of 1 ms.
Assuming that fCPU is 8 MHz and a prescaler divi-
sion factor of 256 will be programmed using the
PR[2:0] bits in the TBUCSR register, 1 ms = 32
TBU timer ticks.
In this case, the initial value to be loaded in the
TBUCV must be (256-32) = 224 (E0h).
ld A, E0h
ld TBUCV, A
; Initialize counter value
ld A 1Fh
;
ld TBUCSR, A
; Prescaler factor = 256,
; interrupt enable,
; TBU enable
Figure 35. TBU Block Diagram
TBU 8-BIT UPCOUNTER (TBUCV REGISTER)
INTERRUPT REQUEST
TBU PRESCALER
fCPU
TBUCSR REGISTER
PR1
PR0
PR2
TCEN
ITE
OVF
MSB
LSB
ART PWM TIMER 8-BIT COUNTER
MSB
LSB
CAS
0
1
TBU
ART TIMER CARRY BIT
0
1
相关PDF资料
PDF描述
ST72632K2B1/XXX 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDIP32
ST72E631K4D0 8-BIT, UVPROM, 8 MHz, MICROCONTROLLER, PDIP32
ST72633K1M1/XXX 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDSO34
ST7263BK1M1/XXX 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDSO34
ST72F63BE4M1 8-BIT, FLASH, 8 MHz, MICROCONTROLLER, PDSO24
相关代理商/技术参数
参数描述
ST7263-EMU2 功能描述:仿真器/模拟器 ST7 Emulator Board RoHS:否 制造商:Blackhawk 产品:System Trace Emulators 工具用于评估:C6000, C5000, C2000, OMAP, DAVINCI, SITARA, TMS470, TMS570, ARM 7/9, ARM Cortex A8/R4/M3 用于:XDS560v2
ST7265X-EVAL/MS 制造商:STMicroelectronics 功能描述:ST6 EVAL BD - Bulk
ST7265X-EVAL/PFD 制造商:STMicroelectronics 功能描述:USB FLASH EVAL - Bulk
ST7266 制造商:6940 功能描述:ST7266
ST7267C8T1L 制造商:STMicroelectronics 功能描述: