MicroMod Asset Tracker Carrier Board Hookup Guide
The MicroMod Asset Tracker has a lot going on so buckle up. In this section we'll cover the various components and hardware included on the Asset Tracker.
Most SparkFun MicroMod Carriers will have some common components and all MicroMod Carriers will have the keyed M.2 MicroMod Connector to plug your processor into. The photo and list below outline some of the components you can expect on most SparkFun MicroMod Carriers.
- M.2 MicroMod Connector - This special keyed M.2 connector lets you install your MicroMod Processor of choice on your Asset Tracker Carrier Board.
- USB-C Connector - Connect to your computer to program your Processor and also can provide power to your MicroMod system.
- 3.3V Regulator - Provides a regulated 3.3V and sources up to 1A.
- Qwiic Connector - The standard Qwiic connector so you can add other Qwiic devices to your MicroMod system.
- Boot/Reset Buttons - Push buttons to enter Boot Mode on Processor boards and to Reset your MicroMod circuit.
- microSD Slot - Insert a microSD card for reading and writing data.
- RTC Battery - We've included a 3V Lithium Rechargeable Battery as a backup power source for the Processor Board Real Time Clock (if present).
The heart of the Asset Tracker is the SARA-R510M8S module from u-blox. This module does so much, it is difficult to know where to begin!
Designed to last an IoT lifetime, this module is 5G-ready with the u-blox UBX-R5 chipset. It has built-in end-to-end security with hardware-based root of trust inside a discrete secure element. It provides a full security suite with foundation, design and end-to-end security, as well as access control. The built-in u‑blox M8 GNSS receiver provides accurate and reliable positioning, always and everywhere. It is optimized for ultra-low power consumption and critical firmware updates can be delivered and services enabled via uFOTA (Firmware Over The Air). There. We told you it did a lot!
The SARA-R5 supports many different forms of data communication from full TCP/IP sockets and packet switched data, through HTTP Get/Put/Post, FTP (the SARA has a built-in file system), Ping, to good old SMS text messaging! The built-in GNSS receiver provides NMEA format data and our library looks after the parsing for you.
The connection between the SARA-R5 and the MicroMod Processor Board is serial (3.3V UART) but again, with this module being so clever, it can communicate over two serial interfaces at the same time. Want your LTE data on one interface and your GNSS data on a separate interface? It can do that too!
LTE and GNSS connections are via separate, robust SMA connectors. Switchable 3.3V power for an active antenna is available on the GNSS connector. The Asset Tracker includes a socket for a Nano SIM.
If you need to, you can manually turn the SARA off by pushing and holding the SARA On button. The SARA will disconnect from the network before going into low power sleep. Press the button briefly to turn the SARA back on again.
The Asset Tracker carries the same ICM-20948 9-Degree Of Freedom Inertial Measurement Unit as OpenLog Artemis. It can provide fast accelerometer, gyro and magnetometer data and can be configured for “Wake On Motion” too. We have a WOM example ready to go. It has a built-in temperature sensor too.
Thieves are wily these days. When attempting to steal your asset, one of the first things they will do is cover or break the antenna (if they can see it). The built-in SPH0641 digital microphone can be used to send an alert as soon as the Asset Tracker hears the thieves coming!
Battery Charging and Monitoring Circuit
Since many applications for the Asset Tracker involve a battery-powered circuit, the board includes both the MCP73831 LiPo battery charger and the MAX17048 battery fuel gauge. The MCP7381 Single-cell charge management IC can deliver a charge current up to 500mA. The MAX17048 is a low-power I2C fuel gauge to monitor your battery's remaining charge.
Plated Through-Hole (PTH) Connections
We've broken out dedicated PTHs for digital, analog, pulse width modulation (PWM), I2C and SPI along the sides of the Asset Tracker Carrier Board. You may also notice that we've included a ground rail next to the digital, analog and PWM pins.
We've also provided PTHs for monitoring and accessing the following power circuits:
- VIN - The power rail fed by USB-C and/or the LiPo battery.
- 3.3V - The regulated 3.3V rail which feeds most of the components on the board. You can measure the 3.3V current draw using the MEAS pins (see below).
- VCCIO - This is the 1.8V rail generated by the SARA-R5. We use it to power the 1.8V to 3.3V level shifters for the UART and I2C connections.
- 1.8V - This is the 1.8V rail which powers the IMU. You can disable it by pulling the MicroMod G4 digital pin LOW.
- RST - Pull this low to reset the MicroMod Processor and the SARA-R5.
The following SARA-R5 I/O connections are also broken out to PTH headers:
- NI - This is the SARA's Network Indicator signal. It will be low (0V) when the network is available, and high (3.3V) when the network is not available.
- TP - This is the Timing Pulse (1PPS) signal and is connected to SARA GPIO6/TP. It will pulse low and high when the SARA is receiving a GNSS signal and the timing pulse has been enabled. Please see Example11 for more details.
- SARA USB D-/D+/DET - These PTHs provide access to the SARA's diagnostic USB port. This connection is only used to access the SARA's trace log. You cannot (currently) upgrade the SARA via this interface. Please consult the SARA R5 Integration Manual for more details.
- SARA I2C - These 3.3V (level-shifted) PTHs can be used to access the SARA's I2C bus. Some models of the SARA-R5 use I2C to communicate with an external GNSS module. As the SARA-R510M8S has GNSS built-in, it is unclear what you might want to use them for. But, we've been diligent and have broken them out anyway!
SWD Programming Pins
An unpopulated JTAG footprint is available for more advanced users who need breakpoint level debugging. Note that this is not populated so you will need a compatible header and compatible JTAG programmer to connect.
On the rear of the board, you will find a large number of jumpers which you can use to connect and disconnect several of the connections between the SARA and the MicroMod Processor:
The tables below outline all of the jumpers on the Asset Tracker along with brief descriptions of their functionality.
|Jumper Name/Label||Description||Default State||Notes|
|G0 / SD CS||Ties the µSD Chip Enable to G0||CLOSED|
|G1 / SD PWR||Toggles 3.3V to control power the µSD card.||CLOSED||Open to isolate G1. µSD will default to always on.|
|G2 / LTE_PWR||Connects G2 to the SARA-R5 ON signal via a level-shifting circuit.||CLOSED||Allows G2 to function in the exact same way as the SARA On button. Cut the jumper to isolate G2 if required.|
|G3 / IMU PWR||When closed, G3 can be used to control power for the IMU via software. By default, IMU power is always on.||OPEN||On the ESP32 Processor G3 is linked directly to the processor's TX1 pin. Leave the G3 jumper OPEN if you are using the ESP32 Processor or else serial communication with the SARA will not work.|
|G4 / RI||When closed, connects G4 to the SARA-R5's Ring Indicator pin.||OPEN||On the ESP32 Processor, G4 is shared with the processor's RX1 pin. Similarly, G4 is shared with SPI CIPO on the RP2040 Processor. Leave this jumper OPEN if using either Processor to avoid serial communication errors with the SARA.|
|G5 / SARA INT||When closed, connects G5 with either the SARA-R5's Interrupt I/O pin or the SARA's GPIO3 I/O pin depending on the state of the EXT INT / GPIO3 dual jumper (covered below).||OPEN||On the RP2040 Processor, G5 is shared with SPI Chip Select line. Closing the jumper will interfere with the SPI bus on the RP2040 Processor.|
|G6 / SARA ON||When closed, this jumper allows G6 to monitor if the SARA power is on.||OPEN||This signal is different to the SARA On push-button. On the RP2040 Processor, G6 is shared with the SPI Clock line. Closing this jumper will interfere with the SPI bus on the RP2040 Processor.|
|G7 / DSR||When closed, connects G7 to the SARA's DSR signal.||OPEN||On the RP2040 Processor, G7 is shared with the SPI COPI line. Leave this jumper open to avoid interfering with the SPI bus on this processor.|
|PDM DAT||Connects the data signal from on-board microphone to AUD_LRCLK (MicroMod Pad 52).||CLOSED||On the RP2040 Processor, AUD_LRCLK is shared with CTS1. Open this jumper to use the CTS connection on the SARA.|
|PDM CLK||Connects the clock signal from the on-board microphone to AUD_BCLK (MicroMod Pad 50).||CLOSED||On the RP2040 Processor, AUD_BCLK is shared with RTS1. Open this jumper to use the RTS connection on the SARA.|
|I2C||A dual jumper that ties SDA & SCL on the primary I2C/Qwiic bus to 3.3V via a pair of 2.2kΩ resistors.||CLOSED||Open both jumpers to disconnect the pull-ups.|
|SARA I2C||A dual jumper that ties the SARA's SDA and SCL lines to 3.3V via a pair of 2.2kΩ||CLOSED||Open both jumpers to disable the pull-ups.|
|CIPO||Ties SPI CIPO/SDI to 3.3V via a 2.2kΩ resistor.||CLOSED||Open to disconnect the pull-up. Opening this jumper may be advantageous for very low power applications where Processors like the Artemis have internal pull-ups which can be used instead.|
|EXT INT / GPIO3||A dual jumper used to select which signal is connected to MicroMod G5.||SEE NOTE||By default, this jumper is set so if the G5 / SARA INT jumper is closed, G5 is connected to the SARA EXT INT I/O pin. Switch this jumper to the opposite side to connect G5 to the SARA GPIO3 pin.|
|DSR||A dual jumper used to control the direction of DSR from input to output .||SEE NOTE||By default, this jumper sets DSR as an input. Switching it sets DSR as an output so users can use dual-UART communication modes on the SARA.|
|MEAS||Allows users to measure the current draw from the 3.3V power rail.||CLOSED||Open this jumper and complete the circuit using a digital multimeter to measure current draw on the 3.3V power rail.|
|VIN/3||Completes the VIN/3 voltage divider circuit.||CLOSED||Open the jumper to disable the VIN/3 voltage divider circuit. Disabling this can be useful in very low power applications to reduce total current draw.|
|3V3 (LED)||Connects the anode of the 3.3V LED to 3.3V via a 1kΩ resistor.||CLOSED||Open the jumper to disable the 3.3V LED to reduce total current draw of the MicroMod circuit.|
|VIN (LED)||Connects the anode of the VIN LED to VIN (5V if powered by USB, 3.7V nominal if powered by LiPo battery) via a 4.7kΩ resistor.||CLOSED||Open the jumper to disable the VIN LED to reduce the total current draw of the MicroMod circuit.|
|ICM_INT||Connects the ICM IMU Interrupt pin to the primary I2C Interrupt pin (I2C_INT) on the MicroMod connector.||CLOSED||Open the jumper to isolate the MicroMod I2C_INT pin from the ICM-20948. On the RP2040 Processor, I2C_INT is shared with TX2. You may need to open this jumper to use the DTR handshake signal.|
|Jumper Name/Label||Description||Default State||Notes|
|V USB||Connects VUSB_DET on the SARA's diganostic (trace log) USB port to V_USB (5V||OPEN||Important! You must not have a Processor installed to use the diagnostic USB port.|
|USB D+||Connects USB_D+ on the SARA's diagnostic (trace log) USB port to USB_D+ on the USB-C connector.||OPEN||Important! You must not have a Processor installed to use the diagnostic USB port.|
|USB_D-||Connects USB_D- on the SARA's diagnostic (trace log) USB port to USB_D- on the USB-C connector.||OPEN||Important! You must not have a Processor installed to use the diagnostic USB port.|
|VE||When closed, allows the Processor to disable the main 3.3V regulator via the 3.3V_EN pin.||OPEN||Recommended only for very low power applications. The Processor can draw power from the RTC battery while the voltage regulator is disabled.|
|BYP||Bypasses the 6V/2A fuse and nets VIN and V_USB together.||OPEN||The "penny-in-the-fuse" jumper. Close only if you know what you are doing!|
Wondering what the pins are that are broken out on the MicroMod Asset Tracker Carrier Board? The tables below outline the Asset Tracker pinout as well as the general MicroMod pinout. Remember to compare the pins against your Processor Board to determine which pins are available.
|M.2 Connector Pin#||MicroMod Pin Name||Asset Tracker Connection||Description|
|2||3.3V||3.3V||Regulated 3.3V via USB-C.|
|3||USB_D+||Passthrough||USB D+ connection for Processor Board.|
|4||3.3V_EN||3.3V Enable||Voltage regulator enable input.|
|5||USB_D-||Passthrough||USB D- connection for Processor Board.|
|6||RESET||RESET Button||Connected to RESET Button. Reset is active LOW|
|9||USB_VIN||VIN||Input voltage from USB.|
|10||D0||SPI PTH CS/D0 PTH||SPI Chip Select for SPI PTH Header. D0 also broken out for I/O PTHs|
|11||BOOT||BOOT Button||Connected to BOOT Button. Boot is active LOW.|
|12||I2C_SDA||I2C_SDA||I2C data for Fuel Gauge & Qwiic connector|
|13||UART_RTS1||SARA RTS_I||UART Request to Send for SARA|
|14||I2C_SCL||I2C_SCL||I2C clock for Fuel Gauge & Qwiic connector|
|15||UART_CTS1||SARA CTS_O||UART Clear to Send for SARA|
|16||I2C_INT#||IMU INT||IMU Interrupt pin|
|17||UART_RX1||SARA TXD_O||SARA UART Data Iutput|
|18||D1||D1||General digital I/O PTH|
|19||UART_TX1||SARA TXD_I||SARA UART Data Output|
|20||UART_RX2||SARA DCD_O/RXD2_O||SARA UART Data Carrier Detect / AUX UART Data Output|
|21||SWDCK||SWDCK||Serial Wire Debug Clock|
|22||UART_TX2||SARA DTR_I/TXD2_I||SARA UART Data Terminal Ready / AUX UART Data Input|
|23||SWDIO||SWDIO||Serial Wire Debug I/O|
|34||A0||A0||A0 PTH (Input Only)|
|34||A1||A1||A1 PTH (Input Only)|
|40||G0/BUS0||SD CS||General purpose pin configured for Chip Select on µSD.|
|42||G1/BUS1||microSD_PWR||General purpose pin configured for µSD Power Enable|
|44||G2/BUS2||LTE_PWR_ON||General purpose pin configured for turning SARA on/off|
|46||G3/BUS3||ICM_PWR||General purpose pin configured for controlling IMU power|
|48||G4/BUS4||SARA RI_O/CTS2_O||SARA UART Ring Indicator / AUX UART Clear to Send|
|49||BATT_VIN/3||VIN/3||Divided input voltage for monitoring power supply.|
|50||AUD_BCLK||I2S_SCK/PDM_CLK||Microphone PDM clock signal|
|51||I2C_SDA1||SARA I2C SDA||SARA I2C data signal|
|52||AUD_LRCLK||I2S_WS/PDM_DAT||Microphone PDM data signal|
|53||I2C_SCL1||SARA I2C SCL||SARA I2C clock signal|
|55||SPI_CS#||ICM_CS||Chip select for IMU level shifting IC|
|59||SPI_COPI||SPI_SDO||SPI controller out/peripheral in|
|61||SPI_CIPO||SPI_SDO||SPI controller in/peripheral out|
|69||G7/BUS7||SARA DSR_O/RTS2_I||SARA UART Data Set Ready / AUX UART Request to Send|
|71||G6/BUS6||SARA_ON||General purpose pin conifgured to monitor power for SARA|
|72||RTC_3V||RTC_3V||3V output for backup battery charging.|
|73||G5/BUS5||SARA_INT||General purpose pin configured for SARA Interrupt I/O pin|
|74||3.3V||3.3V||3.3V output from voltage regulator|
|3.3V||74||73||G5 / BUS5|
|RTC_3V_BATT||72||71||G6 / BUS6|
|SPI_CS1#||SDIO_DATA3 (I/O)||70||69||G7 / BUS7|
|SPI COPI1||SDIO_CMD (I/O)||62||61||SPI_CIPO (I)|
|SPI SCK1||SDIO_SCK (O)||60||59||SPI_COPI (O)||LED_DAT|
|AUD_MCLK (O)||58||57||SPI_SCK (O)||LED_CLK|
|PDM_CLK||PCM_CLK||I2S_SCK||AUD_BCLK||50||49||BATT_VIN / 3 (I - ADC) (0 to 3.3V)|
|G4 / BUS4||48||47||PWM1|
|G3 / BUS3||46||45||GND|
|G2 / BUS2||44||43||CAN_TX|
|G1 / BUS1||42||41||CAN_RX|
|G0 / BUS0||40||39||GND|
|Module Key||30||29||Module Key|
|Module Key||28||27||Module Key|
|Module Key||26||25||Module Key|
|UART_RX2 (I)||20||19||UART_RX1 (I)|
|I2C_SCL (I/0)||14||13||UART_RTS1 (O)|
|I2C_SDA (I/0)||12||11||BOOT (I - Open Drain)|
|RESET# (I - Open Drain)||6||5||USB_D-|
|Signal Group||Signal||I/O||Description||Voltage||Power||3.3V||I||3.3V Source||3.3V|
|GND||Return current path||0V|
|USB_VIN||I||USB VIN compliant to USB 2.0 specification. Connect to pins on processor board that require 5V for USB functionality||4.8-5.2V|
|RTC_3V_BATT||I||3V provided by external coin cell or mini battery. Max draw=100μA. Connect to pins maintaining an RTC during power loss. Can be left NC.||3V|
|3.3V_EN||O||Controls the carrier board's main voltage regulator. Voltage above 1V will enable 3.3V power path.||3.3V|
|BATT_VIN/3||I||Carrier board raw voltage over 3. 1/3 resistor divider is implemented on carrier board. Amplify the analog signal as needed for full 0-3.3V range||3.3V|
|Reset||Reset||I||Input to processor. Open drain with pullup on processor board. Pulling low resets processor.||3.3V|
|Boot||I||Input to processor. Open drain with pullup on processor board. Pulling low puts processor into special boot mode. Can be left NC.||3.3V|
|USB||USB_D±||I/O||USB Data ±. Differential serial data interface compliant to USB 2.0 specification. If UART is required for programming, USB± must be routed to a USB-to-serial conversion IC on the processor board.|
|USB Host||USBHOST_D±||I/O||For processors that support USB Host Mode. USB Data±. Differential serial data interface compliant to USB 2.0 specification. Can be left NC.|
|CAN||CAN_RX||I||CAN Bus receive data.||3.3V|
|CAN_TX||O||CAN Bus transmit data.||3.3V|
|UART||UART_RX1||I||UART receive data.||3.3V|
|UART_TX1||O||UART transmit data.||3.3V|
|UART_RTS1||O||UART request to send.||3.3V|
|UART_CTS1||I||UART clear to send.||3.3V|
|UART_RX2||I||2nd UART receive data.||3.3V|
|UART_TX2||O||2nd UART transmit data.||3.3V|
|I2C||I2C_SCL||I/O||I2C clock. Open drain with pullup on carrier board.||3.3V|
|I2C_SDA||I/O||I2C data. Open drain with pullup on carrier board||3.3V|
|I2C_INT#||I||Interrupt notification from carrier board to processor. Open drain with pullup on carrier board. Active LOW||3.3V|
|I2C_SCL1||I/O||2nd I2C clock. Open drain with pullup on carrier board.||3.3V|
|I2C_SDA1||I/O||2nd I2C data. Open drain with pullup on carrier board.||3.3V|
|SPI||SPI_COPI||O||SPI Controller Output/Peripheral Input.||3.3V|
|SPI_CIPO||I||SPI Controller Input/Peripheral Output.||3.3V|
|SPI_CS#||O||SPI Chip Select. Active LOW. Can be routed to GPIO if hardware CS is unused.||3.3V|
|SPI/SDIO||SPI_SCK1/SDIO_CLK||O||2nd SPI Clock. Secondary use is SDIO Clock.||3.3V|
|SPI_COPI1/SDIO_CMD||I/O||2nd SPI Controller Output/Peripheral Input. Secondary use is SDIO command interface.||3.3V|
|SPI_CIPO1/SDIO_DATA0||I/O||2nd SPI Peripheral Input/Controller Output. Secondary use is SDIO data exchange bit 0.||3.3V|
|SDIO_DATA1||I/O||SDIO data exchange bit 1.||3.3V|
|SDIO_DATA2||I/O||SDIO data exchange bit 2.||3.3V|
|SPI_CS1/SDIO_DATA3||I/O||2nd SPI Chip Select. Secondary use is SDIO data exchange bit 3.||3.3V|
|Audio||AUD_MCLK||O||Audio master clock.||3.3V|
|AUD_OUT/PCM_OUT/I2S_OUT/CAM_MCLK||O||Audio data output. PCM synchronous data output. I2S serial data out. Camera master clock.||3.3V|
|AUD_IN/PCM_IN/I2S_IN/CAM_PCLK||I||Audio data input. PCM syncrhonous data input. I2S serial data in. Camera periphperal clock.||3.3V|
|AUD_LRCLK/PCM_SYNC/I2S_WS/PDM_DATA||I/O||Audio left/right clock. PCM syncrhonous data SYNC. I2S word select. PDM data.||3.3V|
|AUD_BCLK/PCM_CLK/I2S_CLK/PDM_CLK||O||Audio bit clock. PCM clock. I2S continuous serial clock. PDM clock.||3.3V|
|SWD||SWDIO||I/O||Serial Wire Debug I/O. Connect if processor board supports SWD. Can be left NC.||3.3V|
|SWDCK||I||Serial Wire Debug clock. Connect if processor board supports SWD. Can be left NC.||3.3V|
|ADC||A0||I||Analog to digital converter 0. Amplify the analog signal as needed to enable full 0-3.3V range.||3.3V|
|A1||I||Analog to digital converter 1. Amplify the analog signal as needed to enable full 0-3.3V range.||3.3V|
|PWM||PWM0||O||Pulse width modulated output 0.||3.3V|
|PWM1||O||Pulse width modulated output 1.||3.3V|
|Digital||D0||I/O||General digital input/output pin.||3.3V|
|D1/CAM_TRIG||I/O||General digital input/output pin. Camera trigger.||3.3V|
|General/Bus||G0/BUS0||I/O||General purpose pins. Any unused processor pins should be assigned to Gx with ADC + PWM capable pins given priority (0, 1, 2, etc.) positions. The intent is to guarantee PWM, ADC and Digital Pin functionality on respective ADC/PWM/Digital pins. Gx pins do not guarantee ADC/PWM function. Alternative use is pins can support a fast read/write 8-bit or 4-bit wide bus.||3.3V|
|G8||I/O||General purpose pin||3.3V|
|G9/ADC_D-/CAM_HSYNC||I/O||Differential ADC input if available. Camera horizontal sync.||3.3V|
|G10/ADC_D+/CAM_VSYNC||I/O||Differential ADC input if available. Camera vertical sync.||3.3V|
|G11/SWO||I/O||General purpose pin. Serial Wire Output||3.3V|
The Asset Tracker Carrier Board measures 3.0 inches by 3.0 inches (76.2mm x 76.2mm) and has four mounting holes that fit a 4-40 screw.