EFM32TG210F32 Energy Micro, EFM32TG210F32 Datasheet - Page 328

• Manufacturer Part Number: EFM32TG210F32
• Description: MCU 32BIT 32KB FLASH 32-QFN
• Manufacturer: Energy Micro
• Series: Tiny Geckor

Specifications of EFM32TG210F32

• 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, POR, PWM, WDT
• Number Of I /o: 24
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.8 V
• Data Converters: A/D 4x12b, D/A 1x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-VQFN Exposed Pad
• Processor Series: EFM32
• Core: ARM Cortex-M3
• Data Bus Width: 32 bit
• Data Ram Size: 32 KB
• Interface Type: UART, I2C, SPI
• Maximum Clock Frequency: 32 MHz
• Number Of Programmable I/os: 17
• Number Of Timers: 1
• Operating Supply Voltage: 1.8 V to 3.8 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Processor To Be Evaluated: EFM32TG210
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

21.3.14.2 LC sensor
2010-12-21 - d0034_Rev0.90
Figure 21.10. Capacitive sense setup
The following steps show how to configure LESENSE to scan through the four buttons 100 times per
second, issuing an interrupt if one of them is pressed.
1. Assuming LFACLK
2. Enable channels 0 through 3 in CHEN and set IDLECONF for these channels to DISABLED. In
3. Configure the ACMP to operate in CAPSENSE mode, refer to Section 22.3.5 (p. 366) for details.
4. Configure the following bit fields in CHx_CONF, for channels 0 through 3:
5. Set CTRTHRESHOLD to an appropriate value. An interrupt will be issued if the counter value for a
6. Enable interrupts on channels 0 through 3.
7. Start scan sequence by writing a 1 to START in CMD.
In a capacitive sense application, it might be required to calibrate the threshold values on a periodic
basis, this is done in order to compensate for humidity and other physical variations. LESENSE is able
to store up to 16 counter values from a configurable number of channels, making it possible to collect
sample data while in EM2. When calibration is to be performed, the CPU only has to be woken up for a
short period of time as the data to be processed already lies in the result registers. To enable storing of
the count value for a channel, set STRSAMPLE in the CHx_INTERACT register.
Figure 21.11 (p. 328) below illustrates how the EFM32TG can be set up to monitor four LC sensors.
Figure 21.11. LC sensor setup
LESENSE can be used to excite and measure the damping factor in LC sensor oscillations. To measure
the damping factor, the ACMP can be used to generate a high output each time the sensor voltage
exceeds a certain level. These pulses are counted using an asynchronous counter and compared with
the LESENSE scan frequency 100Hz.
capacitive sense mode, the GPIO should always be disabled (analog input).
a. Set EXTIME to 0. No excitation is needed in this mode.
b. Set SAMPLE to COUNTER and COMP to LESS. This makes LESENSE interpret a sensor as
c. Set SAMPLEDLY to an appropriate value, each sensor will be measured for SAMPLEDLY/
sensor is below this threshold after the measurement phase.
active if the frequency on a channel drops below the threshold, i.e. the button is pressed.
LFACLK
LESENSE
ACMP0_CH0
ACMP0_CH1
ACMP0_CH2
ACMP0_CH3
LESENSE
ACMP0_CH0
ACMP0_CH1
ACMP0_CH2
ACMP0_CH3
seconds. MEASUREDLY should be set to 0
DAC0_OUT0
EFM32
is 32kHz, set PCPRESC to 3 and PCTOP to 39 in CTRL. This will make
EFM32
...the world's most energy friendly microcontrollers
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