EFM32G200F64 Energy Micro, EFM32G200F64 Datasheet - Page 295

• Manufacturer Part Number: EFM32G200F64
• Description: MCU 32BIT 64KB FLASH 32-QFN
• Manufacturer: Energy Micro
• Series: Geckor

Specifications of EFM32G200F64

• 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: 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 4x12b, D/A 1x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-VQFN Exposed Pad
• Processor Series: EFM32G200
• 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: 24
• Number Of Timers: 2
• 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

21.3.5.2 Continuous Output Generation
2010-09-06 - d0001_Rev1.00
Example 21.2. LETIMER Continuous Output Generation
In some scenarios, it might be desired to make LETIMER generate a continuous waveform. Very simple
constant waveforms can be generated without the repeat counter as shown in Figure 21.6 (p. 293) , but
to generate changing waveforms, using the repeat counter and buffer registers can prove advantageous.
For the example in Figure 21.10 (p. 295) , the goal is to produce a pulse train consisting of 3 sequences
with the following properties:
• 3 pulses with periods of 3 cycles
• 4 pulses with periods of 2 cycles
• 2 pulses with periods of 3 cycles
Figure 21.10. LETIMER Continuous Operation
The first two sequences are loaded into the LETIMER before the timer is started.
LETIMERn_COMP0 is set to 2 (cycles – 1), and LETIMERn_REP0 is set to 3 for the first sequence, and
the second sequence is loaded into the buffer registers, i.e. COMP1 is set to 1 and LETIMERn_REP1
is set to 4.
The LETIMER is set to trigger an interrupt when LETIMERn_REP0 is done by setting REP0 in
LETIMERn_IEN. This interrupt is a good place to update the values of the buffers. Last but not least
REPMODE in LETIMERn_CTRL is set to buffered mode, and the timer is started.
In the interrupt routine the buffers are updated with the values for the third sequence. If this had not been
done, the timer would have stopped after the second sequence.
The final result is shown in Figure 21.10 (p. 295) . The pulse output is grouped to show which sequence
generated which output. Toggle output is also shown in the figure. Note that the toggle output is not
aligned with the pulse outputs.
Note
LFACLK
UFOA0 = 01
UFOA0 = 10
Int. flags set
LETn_O0
LETn_O1
COMP1
COMP0
LETIMERn
REP0
REP1
Initial configuration,
CNT
REPB just written
1
2
0
3
4
1
2
2
3
4
1
2
1
3
4
UFIF
1
2
0
3
4
1
2
2
2
4
Pulse Seq. 1
1
2
1
2
4
UFIF
1
2
0
2
4
1
2
2
1
4
4
1
2
1
1
REP0IF
UFIF
1
2
0
1
4
4
1
1
1
4
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u
295
4
1
1
0
4
COMP1 = 2
u
REP1 = 2
4
1
1
1
3
Write
u
UFIF
2
1
0
3
2
Pulse Seq. 2
2
1
1
2
2
UFIF
2
1
0
2
2
2
1
1
1
2
REP0IF
UFIF
2
1
0
1
2 2
2
2
2
2
u
2
2
2
1
2
u
2
2
2
0
2
Pulse Seq. 3
u
UFIF
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2
2
2
2
1
u
2
2
2
1
1
REP0IF
final values
u
UFIF
2
Stop,
2
2
0
1
u
2
2
2
0
0
u