EA-APP-002 Embedded Artists, EA-APP-002 Datasheet - Page 13

• Manufacturer Part Number: EA-APP-002
• Description: Development Boards & Kits - ARM LOW POWER APP KIT LPC11U37 (ORYX)
• Manufacturer: Embedded Artists

Specifications of EA-APP-002

• Rohs: yes
• Product: Demonstration Kits
• Tool Is For Evaluation Of: LPC11U37
• Core: ARM Cortex M0
• Interface Type: I2C, USB
• Operating Supply Voltage: 5 V

Copyright 2012 © Embedded Artists AB
Low-power Application Kit (Oryx) - User’s Guide
There is a current consumption cost for keeping the chip active and detecting (single/double) taps.
Exact current consumption depends on setup of detection, for example sample rate. See datasheet for
details. If the chip is placed in standby mode, the current consumption is only 100 nA (= 0.3 uW). The
I2C address to the ADXL345 chip is 0x1D (0.0.1.1.1.0.1.rw). Details about the ADXL345 chip operation
can be found in the datasheet.
The PCF8523 real-time clock is from NXP. The current consumption is very low for keeping the real-
time clock updated, only 150 nA (= 0.45 uW). When communicating with the PCF8523 over I2C, the
current consumption increase to 200 uA (= 600 uW). The communication time is however very short so
the power consumption will in mean typically be very low. There is an interrupt output from the
PCF8523. This signal can for example be used to wake-up the LPC11U37 once a second or when an
alarm time has elapsed. The I2C address to the PCF8523 chip is 0x68 (1.1.0.1.0.0.0.rw). Details about
the PCF8523 chip operation can be found in the datasheet.
The LM75B temperature sensor is from NXP. The current consumption is only 0.2 uA (= 0.6 uW) when
in shutdown mode. While measuring temperature the current consumption increase to 100 uA (= 300
uW) and up to 200 uA (= 600 uW) while communicating over i2c. The I2C address to the LM75B chip
is 0x48 (1.0.0.1.0.0.0.rw). Details about the LM75B chip operation can be found in the datasheet.
3.4.3
There is a 4Mbit SPI flash S25FL004 from Spansion. Details about the S25FL004 chip operation can
be found in the datasheet. The chip is connected to SPI channel #1 of the LPC11U37. The active
current consumption is relatively high, but there are two low-power modes of the chip. One is standby
mode, which it enters automatically when no transfers are active. It then consumes 20 uA (= 60 uW).
There is also a deep power down mode with only 1.5 uA (= 4.5 uW).
There is also a power switch for the S25FL004 in case the 4.5 uW is too much. Then it is possible to
completely remove the chip from the power consumption. PIO1_16 controls the power switch (P-
channel mosfet, Q4). A low signal enables the voltage.
There is a 96x96 pixel memory LCD from Sharp. Details about the LCD operation can be found in the
datasheet. The chip is connected to SPI channel #0 of the LPC11U37. The active current consumption
is very low. The LCD requires a (about) 1 Hz update rate and is then consuming only 4 uA (= 12 uW).
The update rate is not critical and can vary over a range. See datasheet for details.
The display requires a refresh signal (lowest rate is 1 Hz). Currently this is done via the SPI interface
but there is provision for direct control from the RTC (CLKOUT signal). R24 and R25 must be mounted
in this case and R26 removed.
There is also a power switch for the LCD in case the display is not used (or 12 uW is too much). Then
it is possible to completely remove the chip from the power consumption. PIO1_14 controls the power
switch (P-channel mosfet, Q5). A low signal enables the voltage.
3.4.4
The 8 capacitive sensors are implemented with the PCF8885 from NXP. The chip handles all low-level
details of sensing touches. There is a simple I2C interface to the chip. The I2C address to the
PCF8885 chip is 0x20 (0.1.0.0.0.0.0.rw). Details about the PCF8885 chip operation can be found in the
datasheet.
The 8 sensors are independent buy are grouped physically as 4 independent sensors and 4 sensors in
a slider. Slider functionality can be realized with software.
There are two methods for signaling touches to the software;
The capacitive sensors can be used to wake-up the LPC11U37 from low-power modes (via interrupt).
The current consumption cost for keeping the chip active is 10 uA (= 30 uW). This is the cost for having


Polling via an I2C-register
IRQ (interrupt) via PIO0_12.
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