Intel(r) Quark(tm) micrcontroller D2000 based Environmental sensors board

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).

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.

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.

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.

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

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.

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