C8051F131R Silicon Labs, C8051F131R Datasheet - Page 320

• Manufacturer Part Number: C8051F131R
• Description: 8-bit Microcontrollers - MCU 128kB 100MIPS 8448B RAM
• Manufacturer: Silicon Labs

Specifications of C8051F131R

• Product Category: 8-bit Microcontrollers - MCU
• Core: 8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 100 MHz
• Program Memory Size: 128 KB
• Data Ram Size: 8.25 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 2.7 V to 3.6 V
• Package / Case: TQFP-64
• Mounting Style: SMD/SMT
• A/d Bit Size: 10 bit
• A/d Channels Available: 9
• Data Rom Size: 64 KB
• Interface Type: I2C, SMBus, SPI, UART
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 32
• Number Of Timers: 16 bit
• Processor Series: C8051
• Program Memory Type: Flash
• Factory Pack Quantity: 500
• Supply Voltage - Max: 3.6 V
• Supply Voltage - Min: 3 V

C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
23.2.4. Toggle Output Mode (Timer 2 and Timer 4 Only)
Timers 2 and 4 have the capability to toggle the state of their respective output port pins (T2 or T4) to pro-
duce a 50% duty cycle waveform output. The port pin state will change upon the overflow or underflow of
the respective timer (depending on whether the timer is counting up or down ). The toggle frequency is
determined by the clock source of the timer and the values loaded into RCAPnH and RCAPnL. When
counting DOWN, the auto-reload value for the timer is 0xFFFF, and underflow will occur when the value in
the timer matches the value stored in RCAPnH:RCAPnL. When counting UP, the auto-reload value for the
timer is RCAPnH:RCAPnL, and overflow will occur when the value in the timer transitions from 0xFFFF to
the reload value.
To output a square wave, the timer is placed in reload mode (the Capture/Reload Select Bit in TMRnCN
and the Timer/Counter Select Bit in TMRnCN are cleared to ‘0’). The timer output is enabled by setting the
Timer Output Enable Bit in TMRnCF to ‘1’. The timer should be configured via the timer clock source and
reload/underflow values such that the timer overflow/underflows at 1/2 the desired output frequency. The
port pin assigned by the crossbar as the timer’s output pin should be configured as a digital output (see
Section “18. Port Input/Output” on page 235
of the pin. A Read/Write of the Timer’s Toggle Output State Bit (TMRnCF.2) is used to read the state of the
toggle output, or to force a value of the output. This is useful when it is desired to start the toggle of a pin in
a known state, or to force the pin into a desired state when the toggle mode is halted.
320
Equation 23.1. Square Wave Frequency (Timer 2 and Timer 4 Only)
F
sq
=
------------------------------------------------------
2

). Setting the timer’s Run Bit (TRn) to ‘1’ will start the toggle

Rev. 1.4
65536 RCAPn
F
TCLK
–
