EFM32-G8XX-DK Energy Micro, EFM32-G8XX-DK Datasheet - Page 14

• Manufacturer Part Number: EFM32-G8XX-DK
• Description: KIT DEV EFM32 GECKO LCD SUPPORT
• Manufacturer: Energy Micro
• Series: EFM®32r
• Type: MCUr

Specifications of EFM32-G8XX-DK

• Contents: Motherboard, MCU Board, Prototyping Board, Cable, CD
• Processor To Be Evaluated: EFM32G8x
• Data Bus Width: 32 bit
• Interface Type: RS-232, USB, I2C
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Operating Supply Voltage: 5 V
• Silicon Manufacturer: Energy Micro
• Core Architecture: ARM
• Core Sub-architecture: Cortex-M3
• Silicon Family Name: Gecko
• Kit Contents: Mother Board, Prototyping Board, MCU Board, Software Development Environment
• Rohs Compliant: Yes
• Silicon Core Number: EFM32
• For Use With/related Products: EFM32G890F128
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 914-1001

9 Advanced Energy Monitor
9.1 AEM Display
9.2 AEM configuration
9.3 AEM theory of operation
9.4 AEM accuracy and performance
2010-04-09 - t0005_1.10
To enter AEM from the main page, press the pushbutton under the display labeled AEM. If the EFM
is using the display, press the AEM button at the right side of the display, and the board controller will
take control of the display and show the AEM. To return to EFM control, simply press the AEM button
once more.
When the AEM is entered, you will get a real-time graphical display of the current consumption of the
EFM and other circuits powered by the VMCU power rail. The AEM display mainly features a plot of
current the consumption over time. It also displays the latest sampled current consumption and voltage.
There are several parameters that can be configured on the AEM. To configure AEM, first enter the
AEM page. Then push the button labeled CFG. In the CFG page, you can adjust the scale of the time
axis of the current plot.
In order to be able to measure currents ranging from 0.1uA to 50mA (114dB dynamic range), two current
sense amplifiers are utilized. The amplifiers measure voltage drop over a small series resistor and
translates this into a current. Each amplifier is adjusted for current measurement in a specific range.
The ranges for the amplifiers overlap and a change between the two occurs when the current is 200uA.
To reduce noise, averaging of the samples is performed before the current measurement is presented
in the AEM GUI.
During startup of the kit and when VMCU is changed, a calibration of the AEM is performed. This
calibration compensates for the offset error in the sense amplifiers. In order for the calibration to be
correct, no load should be connected between the pins of ST6 during calibration.
The Advanced Energy Monitor is capable of measuring currents in the range of 0.1uA to 50mA. For
currents above 200uA, the AEM is accurate within 0.1mA. When measuring currents below 200uA, the
accuracy increases to 1uA. Even though the absolute accuracy is 1uA in the sub 200uA range, the AEM
is able to detect changes in the current consumption as small as 100nA. The measurement bandwidth
of the AEM is 60Hz when measuring currents below 200uA and 120Hz when measuring currents above
200uA. The table below summarizes accuracy of the two current sense amplifiers in different ranges.
Table 9.1. AEM accuracy
Note
Current range
50mA
1mA
200uA
10uA
1uA
In order for the AEM to work correctly, VMCU should be 3.0V or higher.
Preliminary
Low gain amplifier accuracy
0.1mA
0.1mA
0.01mA
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...the world's most energy friendly microcontrollers
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High gain amplifier accuracy
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1uA
0.1uA
0.1uA
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