Murata Debuts “World’s Smallest LoRa Module”
The Type 1SJ is designed for ISM bands ranging from 868 MHz to 916 MHz, including those employed in the US, Europe, and Asia.
Measuring at 10.0 mm x 8.0 mm x 1.6 mm, Murata’s new LoRaWAN module is said to combine the critical elements of size, range, and security along with low power and low price essential for high volume devices.
Murata’s Type 1SJ LoRa Module. Image used courtesy of Murata
Like STMicroelectronics, which recently claimed the title for "the world's first LoRa SoC," Murata is claiming its own stakes in the LoRa market as the "world’s smallest LoRa module."
The 1SJ is strongly based on Semtech’s SX1262 sub-GHz radio frequency transceiver. This device complies with the physical layer mandates of the LoRaWAN (LoRa wide area network) specification released by the LoRa Alliance.
Semtech's SX1262. Image used courtesy of Semtech
Murata’s LoRa module also incorporates an open STM32L0 microcontroller (MCU) from STMicroelectronics, which is based on the widely familiar Arm Cortex-M0+ core.
The device can support the necessary application layers largely due to its onboard 192kB of Flash memory and 20kB of RAM.
The 1SJ also features a temperature-controlled crystal oscillator (TXCO). The device supports such communications interfaces as I2C, SPI, UART, ADC, and USB, as well as a variety of GPIOs.
The low cost, low power unit is aimed at OEMs designing solutions for fields such as agriculture, smart buildings, smart cities, asset tracking, and utility monitoring. It will also find wide-ranging applications in many areas of the IoT.
What Is LoRa?
LoRa (long range) technology was acquired in its early stages by Semtech, the founding member of the LoRa Alliance.
Diagram of LoRaWAN. Image used courtesy of Semtech
LoRa is a physical layer, and LoRaWAN (LoRa wide area network) is an open standard that is maintained by the LoRa Alliance. LoRaWAN defines the upper layers of the network.
Important Specifications of the Type 1SJ
The unit is FSK and OOK capable. It operates over a frequency range of 869 MHz to 930 MHz.
Murata states that the device's maximum transmit power of the LoRa module is +22 dBm. At that level, the transmit mode current is 118 mA. The receiver sensitivity is -137 dBm at a 125 kHz BW, and in that mode, the device draws 15.5 mA.
The Type 1SJ operates with a maximum supply voltage of 3.9 V and is RoHS compliant. Its operating temperature can range from -40ºC to +85ºC.
Low Power Consumption
The Type 1SJ is meant to form the basis of products that can operate for “years on a single battery.” As such, the module features multiple low power modes that allow it to operate while drawing a typical current of 1.3 µA.
Security
Murata’s new LoRa module open MCU can optionally be flashed with a safe code from Trusted Object’s “TO Protect Library.” These software libraries are especially targeted at IoT devices running on Arm (and other) MCUs.
Diagram of the TO protect integrated into an IoT chain of trust. Image used courtesy of Murata and Trusted Objects
This will ensure that the Flash memory is secure and encrypted, protecting the system from cyber threats, especially important for IoT and many other types of edge computing applications.
Around the Industry
LoRa is an extremely popular and widely adapted IoT modality, and Murata has a lot of company in this crowded field.
Microchip’s ATSAMR34J18 comes in a 6 mm x 6 mm BGA package. It incorporates a 32-bit Arm Cortex M0+ MCU, 256K of Flash, and 40 kB of RAM. Receiver sensitivity and maximum transmit power is -148 dBm and +20 dBm, respectively.
The ETH-LORA-M-AX-01 from Ethertronics, claimed to be the first LoRa module, features a receiver sensitivity of -138 dBm and offers a maximum transmitter output +19 dBm. The company has made demo boards available to decrease time to market for OEMs developing products based on the device.
