Intel(r) Quark(tm) Microcontroller D2000 based Environmental Sensors Board

Introduction

This is a fairly small (51 x 51 mm) board, equipped with a low power Intel Quark D2000 microcontroller, and several sensors (accelerator, temperature, humidity, atmospheric pressure), as well as a mikroBUS compatible header and a Grove compatible connectors, that can be used to connect additional sensors, memory, or radio modules. The board can be used to monitor the environment conditions, and store or transmit the data to a remote system for further processing.

Design Overview

Microcontroller

Microcontroller Overview

The board uses the Intel Quark D2000 microcontroller (U1). This microcontroller contains a 32-bit x86 processor core, 25 GPIOs, I2C, SPI interfaces, JTAG, two UART interfaces, PWM module, timers, and so on. It includes 32 KiB of the instruction Flash ROM, 8 KiB of the SRAM, and a few kilobytes of the OTP memory (which is actually a Flash ROM which can be write/erase protected).

Clocks

The microcontroller runs on a 32 MHz clock provided by quartz resonator Y1, it also uses a 32768 Hz quartz resonator Y2 for RTC clock.

Power Supply

The microcontroller includes an on-chip 1.8V buck converter voltage regulator to supply voltage for the CPU core. The 47 uH inductor L1 and the 4.7 uF capacitor C11 are the external components used by the voltage regulator. The ferrite EMI filter FB1 and the capacitor C7 form an LC filter for filtering the analog supply voltage AVDD. The I/O power supply IOVDD rail, as well as all the on-board sensors are connected directly to the CR2032 battery BT1 (nominally 3V). All the power supply rails are bypassed using 1 uF capacitors.

Reset

The board uses a simple RC reset circuit implemented using the resistor R4, the capacitor C1, and reset switch SW1. The Quark D2000 MCU has a hysteresis on RST_N input, which ensures the proper reset signal generation using an RC circuit.

GPIO Pins Allocation

The GPIO pins of the Quark D2000 MCU are allocated on this board as shown in the table below. Note that GPIO pins have multiple functions (modes), and they need to be configured in the software according to the function used by this board. The suggested pin functions are marked with italic bold.

Quark D2000 pin number	Quark D2000 pin name	Function used by the board	Mode 0	Mode 1	Mode 2
31	F0_SPI_M_SS0	mikroBUS - SPI chip select - SS0	GPIO0	AI0	*SPI_M_SS0*
32	F1_SPI_M_SS1	Battery monitor (analog input)	GPIO1	*AI1*	SPI_M_SS1
33	F2_SPI_M_SS2	User switch SW2, 560k pull-up, 1 == switch not pressed	*GPIO2*	AI2	SPI_M_SS2
34	F3_SPI_M_SS3	mikroBUS - analog input A0	GPIO3	*AI3*	SPI_M_SS3
35	F4_RTC_CLK_OUT	Accelerometer interrupt - INT1	*GPIO4*	AI4	RTC_CLK_OUT
36	F5_SYS_CLK_OUT	mikroBUS - interrupt input - INT2	*GPIO5*	AI5	SYS_CLK_OUT
37	F6_I2C_SCL	I2C SCL - on-board sensors, mikroBus, Grove header P7	GPIO6	AI6	*I2C_SCL*
38	F7_I2C_SDA	I2C SDA - on-board sensors, mikroBus, Grove header P7	GPIO7	AI7	*I2C_SDA*
39	F8_SPI_S_SCLK	Grove header P5 - D7	*GPIO8*	AI8	SPI_S_SCLK
11	F9_SPI_S_SDIN	mikroBUS - reset RST, Grove header P5 - D8	*GPIO9*	AI9	SPI_S_SDIN
2	F10_SPI_S_SDOUT	Grove header P6 - D3	*GPIO10*	AI10	SPI_S_SDOUT
3	F11_SPI_S_SCS	Grove header P6 - D2	*GPIO11*	AI11	SPI_S_SCS
4	F12_UART_A_TXD	FTDI compatible UART header P2 - TXD, mikroBus - TXD	GPIO12	AI12	*UART_A_TXD*
5	F13_UART_A_RXD	FTDI compatible UART header P2 - RXD, mikroBus - RXD	GPIO13	AI13	*UART_A_RXD*
6	F14_UART_A_RTS_DE	FTDI compatible UART header P2 - RTS	GPIO14	AI14	*UART_A_RTS*/UART_A_DE
7	F15_UART_A_CTS_RE	FTDI compatible UART header P2 - CTS	GPIO15	AI15	*UART_A_CTS*/UART_A_RE
8	F16_SPI_M_SCLK	mikroBUS - SPI SCLK	GPIO16	AI16	*SPI_M_SCLK*
9	F17_SPI_M_TXD	mikroBUS - SPI MOSI	GPIO17	AI17	*SPI_M_TXD*
10	F18_SPI_M_RXD	mikroBUS - SPI MISO	GPIO18	AI18	*SPI_M_RXD*
18	F19_PWM0_TDO	JTAG header P1 - TDO	*TDO*	GPIO19	PWM0
13	F20_UART_B_TXD_TRST_N	JTAG header P1 - TRST	*TRST*	GPIO20	UART_B_TXD
14	F21_UART_B_RXD_TCK	JTAG header P1 - TCK	*TCK*	GPIO21	UART_B_RXD
15	F22_UART_B_RTS_DE_TMS	JTAG header P1 - TMS	*TMS*	GPIO22	UART_B_RTS/UART_B_DE
16	F23_UART_B_CTS_RE_TDI	JTAG header P1 - TDI	*TDI*	GPIO23	UART_B_CTS/UART_B_RE
21	F24_PWM1	mikroBUS - PWM output, on-board LED D1	*GPIO24*	-	*PWM1*

UART Interface

The UART interface A of the Quark D2000 is exposed on an FTDI compatible header P2. Normally this is used to connect the FTDI USB to serial cable to provide a debug output. The UART interface A TXD and RXD signals are also available on the mikroBUS header, and that can be used to connect sensors that use UART interface.

JTAG interface

The board uses a standard ARM 10-pin JTAG connector P1. The board has been tested with Tin Can Tools Flyswatter2 JTAG adapter and Olimex ARM JTAG 20 pin to 10 pin adapter.

On-board Sensors

Accelerometer and Magnetometer

The board uses Bosch Sensortec BMC150 3-axis accelerometer and magnetometer (U2). This sensor is configured in I2C mode, and uses I2C addresses 0x11 for accelerometer, and 0x13 for magnetometer. The interrupt output INT1 of the accelerometer is connected to GPIO4 of Quark D2000. The interrupt outputs INT2 (accelerometer) and INT3 (magnetometer), as well as DRDY output are available on header P8.

Atmospheric Pressure, Humidity and Temperature Sensor

The board uses Bosch Sensortec BME280 environmental sensor (U3). This sensor provides atmospheric pressure, relative humidity, and temperature measurements. The sensor is configured in I2C mode, and uses I2C address 0x76.

Ambient Light Sensor

The board uses Vishay VEML7700 ambient light sensor (U4). The sensor I2C addess is 0x10.

Bill of Materials

Link to the project on Mouser.com - View and order all components except of PCB.

Link to the project on OSHPark.com - View and order PCB.

Component type	Reference	Description	Quantity	Possible sources and notes
PCB		D2000 Environmental Sensors PCB, V2.1	1	Order from OSH Park or your favorite PCB manufacturers using Gerber files provided below.
Battery	BT1	CR2032 lithium battery	1	Mouser 658-CR2032. Note: Due to shipping restrictions battery is not included in Mouser's project BOM
Battery Holder	BT1	CR2032/CR2025 battery holder, THM	1	Mouser 712-BAT-HLD-001-THM
Capacitor	C1 - C3	0.1 uF multilayer ceramic capacitor, 0603 SMT	3	Mouser 77-VJ0603Y104JXJPBC
Capacitor	C4 - C10	1 uF multilayer ceramic capacitor, 0603 SMT	7	Mouser 810-C1608X7R1E105K
Capacitor	C11	4.7 uF multilayer ceramic capacitor, 0603 SMT	1	Mouser 81-GRM188R61A475KE5D
LED	D1	Green LED, 0603 SMT	1	Mouser 78-VLMG1300-GS08
Ferrite Bead	FB1	Ferrite EMI filter, 120 ohm, 0603 SMT	1	Mouser 81-BLM18PG121SN1D
Inductor	L1	47 uH, 1008 SMT	1	Mouser 810-NLV25T-470J-EF
Connector	P1	2x5 pin header, 1.27 mm pitch, THM	1	Mouser 649-221111-00010T4LF
Connector	P2	1x6 pin header, 2.54 mm pitch, THM	1	Mouser 855-M20-9990645
Connector	P3, P4	1x8 socket, 2.54 mm pitch, THM	2	Mouser 517-929850-01-08-RB
Connector	P5 - P7	4 pin connector, 2 mm pitch, THM	3	Mouser 538-35362-0450
Resistor	R1	220 ohm resistor, 0603 SMT	1	Mouser 71-CRCW0603220RFKEB
Resistor	R2, R3	5.6 kohm resistor, 0603 SMT	2	Mouser 71-CRCW0603-5.6K-E3
Resistor	R4 - R9	560 kohm resistor, 0603 SMT	6	Mouser 71-CRCW0603-560K-E3
Resistor	R10	10 Mohm resistor, 0603 SMT	1	Mouser 71-CRCW060310M0FKEB
Resistor	R11, R12	Do not populate	2	Note: These resistors can be used to set up voltage divider for analog reference voltage.
Tactile Switch	SW1, SW2	Tactile Switch, C&K Components PTS820 series	2	Mouser 611-PTS820J25MSMTR
Integrated Circuit	U1	Intel Quark D2000 MCU	1	Mouser 607-FND2000SR2KF
Integrated Circuit	U2	Bosch BMC150 accelerometer and magnetometer	1	Mouser 262-BMC150
Integrated Circuit	U3	Bosch BME280 atmospheric pressure and humidity sensor	1	Mouser 262-BME280
Integrated Circuit	U4	Vishay VEML7700 ambient light sensor	1	Mouser 78-VEML7700-TR
Crystal	Y1	32 MHz crystal oscillator	1	Mouser 581-CX3225GB32PHPQCC
Crystal	Y2	32768 Hz crystal oscillator	1	Mouser 581-ST2012SB32H5HPWA