EFM32G890F64 Energy Micro, EFM32G890F64 Datasheet - Page 277

• Manufacturer Part Number: EFM32G890F64
• Description: MCU 32BIT 64KB FLASH 112-BGA
• Manufacturer: Energy Micro
• Series: Geckor

Specifications of EFM32G890F64

• Core Processor: ARM® Cortex-M3™
• Core Size: 32-Bit
• Speed: 32MHz
• Connectivity: EBI/EMI, I²C, IrDA, SmartCard, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, DMA, LCD, POR, PWM, WDT
• Number Of I /o: 90
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.8 V
• Data Converters: A/D 8x12b, D/A 2x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 112-LFBGA
• Processor Series: EFM32G890
• Core: ARM Cortex-M3
• Data Bus Width: 32 bit
• Data Ram Size: 16 KB
• Interface Type: I2C, UART
• Maximum Clock Frequency: 32 MHz
• Number Of Programmable I/os: 90
• Number Of Timers: 3
• Operating Supply Voltage: 1.8 V to 3.8 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

20.3.1 Counter
20.3.1.1 Clock Source
2010-09-06 - d0001_Rev1.00
Figure 20.1. RTC Overview
The RTC is enabled by setting the EN bit in the RTC_CTRL register. It counts up as long as it is
enabled, and will on an overflow simply wrap around and continue counting. The RTC is cleared when it
is disabled. The timer value is read-only and the RTC always starts counting from 0 when enabled. The
value of the counter can be read using the RTC_CNT register.
The RTC clock source and its prescaler value are defined in the Register Description section of the Clock
Management Unit (CMU). The clock used by the RTC has a frequency given by Equation 20.1 (p. 277) .
RTC Frequency Equation
where f
278) shows the time of overflow and resolution of the RTC at the available prescaler values.
To use this module, the LE interface clock must be enabled in CMU_HFCORECLKEN0 in addition to
the module clock
LFACLK
LFACLK
RTC
Clear
Counter (CNT)
is the LFACLK frequency (32.768 kHz) and RTC_PRESC is a 4 bit value. Table 20.1 (p.
Com pare 0
(COMP0)
f
RTC
=
= f
Peripheral bus
LFACLK
/2
...the world's most energy friendly microcontrollers
277
RTC_PRESC
Com pare 1
(COMP1)
=
RTC Control and
Status
Com pare m atch 0
Com pare m atch 1
www.energymicro.com
(20.1)