AT89C5131A-M Atmel Corporation, AT89C5131A-M Datasheet - Page 54

• Manufacturer Part Number: AT89C5131A-M
• Manufacturer: Atmel Corporation

Specifications of AT89C5131A-M

• Flash (kbytes): 32 Kbytes
• Max. Operating Frequency: 48 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Sram (kbytes): 1.25
• Eeprom (bytes): 1024
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART/USB
• Watchdog: Yes

Figure 13-1. Auto-reload Mode Up/Down Counter (DCEN = 1)
13.2
54
Programmable Clock Output
AT89C5130A/31A-M
F
CLK PERIPH
In the Clock-out mode, Timer 2 operates as a 50%-duty-cycle, programmable clock generator
(See Figure 13-2). The input clock increments TL2 at frequency F
edly counts to overflow from a loaded value. At overflow, the contents of RCAP2H and RCAP2L
registers are loaded into TH2 and TL2. In this mode, Timer 2 overflows do not generate inter-
rupts. The following formula gives the Clock-out frequency as a function of the system oscillator
frequency and the value in the RCAP2H and RCAP2L registers
For a 16 MHz system clock, Timer 2 has a programmable frequency range of 61 Hz
(F
(P1.0).
Timer 2 is programmed for the Clock-out mode as follows:
• Set T2OE bit in T2MOD register.
• Clear C/T2 bit in T2CON register.
• Determine the 16-bit reload value from the formula and enter it in RCAP2H/RCAP2L
• Enter a 16-bit initial value in timer registers TH2/TL2. It can be the same as the reload value
• To start the timer, set TR2 run control bit in T2CON register.
CLK PERIPH
registers.
or a different one depending on the application.
/2
16)
to 4 MHz (F
Clock OutFrequency
: 6
–
(UP COUNTING RELOAD VALUE)
(DOWN COUNTING RELOAD VALUE)
CLK PERIPH
RCAP2L
T2
(8-bit)
(8-bit)
(8-bit)
TL2
FFh
/4). The generated clock signal is brought out to T2 pin
T2CON
RCAP2H
=
C/T2
(8-bit)
(8-bit)
TH2
(8-bit)
0
FFh
1
---------------------------------------------------------------------------------------- -
4
×
(
65536 RCAP2H
T2CON
TR2
F
–
CLKPERIPH
T2EX:
if DCEN = 1, 1 = UP
if DCEN = 1, 0 = DOWN
if DCEN = 0, up counting
T2CON
TOGGLE
TF2
CLK PERIPH
⁄
RCAP2L
T2CON
EXF2
INTERRUPT
Timer 2
/2. The timer repeat-
)
4337K–USB–04/08