2018 – Beyondlogic

Review: RAK8213 LTE Cat M1/NB1 IoT Modem

November 1, 2018 Craig Peacock 4

The RakWireless RAK8213 is a Quectel BG96 based 4G LTE Cat M1/Cat NB1/EGPRS modem in a PCI Express MiniCard Form Factor. LTE categories M1/NB1 combined with innovations including Power Saving Mode (PSM) and Extended Discontinuous Reception (eDRX) can rival power consumption and battery life of other IoT Technologies such as LoRa and Sigfox. The RAK8213 is available from Aliexpress for just $39.90 USD. The BG96 includes an integrated TCP/IP stack with HTTP and MQTT client, greatly simplifying firmware development. The RAK8213 features: LTE Cat M1, Cat NB1 (NB-IoT) and EGPRS. GNSS – Support for GPS, GLONASS, BeiDou/Compass, Galileo and QZSS. Ultra Low Power. …

An Introduction to chardev GPIO and Libgpiod on the Raspberry PI

October 16, 2018 Craig Peacock 12

Linux 4.8 introduced a new GPIO user space subsystem for accessing GPIO. This tutorial provides an introduction to the new Character Device GPIO and explores how to control GPIO from the command line. sysfs GPIO User-mode GPIO (General Purpose Input/Output) has historically been performed via the legacy “integer-based”sysfs pseudo file system. For example, to set GPIO25, one would: # echo out > /sys/class/gpio/gpio25/direction # echo 1 > /sys/class/gpio/gpio25/value GPIO access via this legacy sysfs interface has been deprecated since version 4.8 of the Linux kernel. chardev GPIO The new way of doing GPIO is via the “descriptor-based” character device ABI (Application Binary …

FTDI FT2232H USB to UART/MPSSE/JTAG Breakout Board

October 15, 2018 Craig Peacock 0

The FTDI FT2232H Hi-Speed Dual USB UART/FIFO Breakout Board provides a variety of standard serial and parallel interfaces: Asynchronous UART JTAG I2C SPI Parallel FIFO The board includes two linear regulators offering either 3.3V or 2.5V IO. An on-board Serial EEPROM stores custom USB descriptors, VID/PIDs and configurations. Design Files Design files can be downloaded from the Circuit Maker website. Circuit Maker is a free EDA tool from Altium. FT2232H Breakout version 1.A.1 Gerbers (Zip) FT2232H Breakout version 1.A.1 Schematics (PDF) The PCB for this design was fabricated by oshpark.com

Compiling U-Boot with Device Tree Support for the Raspberry Pi

October 5, 2018 Craig Peacock 11

U-Boot U-Boot (The Universal Bootloader) is a popular, feature rich, open source bootloader for embedded systems. It is licenced under the GNU General Public Licence version 2. While its primary purpose is to boot an operating system, such as Linux, it also provides many useful tools for developing and debugging embedded systems. This includes support for many common file-systems including FAT, ext3, ext4, NFS etc and interfaces such as USB, Ethernet (IP), MMC and even Asynchronous Serial (Kermit/xmodem/ymodem). This allows the developer to load new images and file-systems from a variety of sources for testing and/or reflashing. It also includes …

RN2903: Using the LoRaWAN™ Library Plug-in for MPLAB® Code Configurator and customising for the AU915 Frequency Plan

September 19, 2018 Craig Peacock 5

The RN2903 Wireless LoRa Module from Microchip ships with an on-board LoRaWAN Class A protocol stack. This stack can be accessed via ASCII based commands over a UART interface. For many, this is the interface of choice, offloading the complexity of the LoRaWAN stack to a dedicated processor contained within the module. Another advantage is Microchip can fully certify the module and stack. I decided not to use the on-board stack for two reasons: Here in Australia, we must use the AU915 frequency plan. Microchip has beta firmware for this frequency plan, but it is not yet publicly available. Developers …

Microchip RN2903 LoRa Transceiver Breakout Board

September 15, 2018 Craig Peacock 4

A breakout board for Microchip’s series of LoRa transceiver modules: RN2483 fully-certified 433/868 MHz Module (Europe) RN2903 fully-certified 915 MHz Module (North America, Australia) The RN2483/RN2903 LoRa modules contain a Microchip PIC18LF46K22 MCU with a Semtech SX1276 radio transceiver and is intended as a complete certified solution with LoRaWAN Class A protocol stack and an ASCII command interface over a UART connection. However, if you want to get under the hood, MicroChip provide details in the LoRaWAN Library Plug-in for MPLAB Code Configurator User’s Guide on how to target the on-board PIC18LF46K22 and customise the module for your own purposes. RN2903 Pin Out (XLSX) Design Files …

ML2032 Coin Cell Charger

September 13, 2018 Craig Peacock 0

This design is intended to recharge Maxell ML2032 Lithium Manganese Dioxide rechargeable coin cell batteries with a nominal voltage of 3.0V. These are ‘special’ coin cell batteries designed specifically as a rechargeable secondary cell. It is not recommended to attempt to recharge a primary CR2032. These cells have not be designed for recharging. Background Rechargeable replacements of the popular CR2032 3V lithium coin cell battery exist, but one caveat is reduced capacity. The common CR2032 from name brand manufacturers such as Panasonic will have a capacity of approximately 220mAh. Rechargeable replacements of the CR2032 appear to come in a range of different chemistries. …

RAK833/RAK2247 LoRaWAN Concentrator

August 29, 2018 Craig Peacock 9

This board is a Raspberry PI Hat for the RAK833/RAK2247 LoRa Concentrator Gateway Modules. The RAK2247 is improved version of the RAK833 with better heatsinking, a boost in the maximum transmission power and improved interference immunity. Both are a smaller version of the popular RAK831. The RAK831 is larger, about the same footprint than a Raspberry PI and requires a breakout board to convert the RAK831’s 24 pin connector to the Raspberry PI’s 40 pin connector. The RAK833 is a more elegant industry standard PCI Express Mini Card form factor (Type F2). The RAK833 module consists of a Semtech SX1301 Digital Baseband chip …

12V 7Ah SLA Low Voltage Disconnect

June 12, 2018 Craig Peacock 0

The 12V 7Ahr “alarm” battery is still a safe, dependable choice for stationary back-up supplies, running items such as LED lighting or modem/routers. Using two Keystone 3571 female PCB terminals, this PCB assembly attaches directly to the terminals of a 12V 7AH SLA Battery (with 4.75mm spade terminals) and provides a low voltage cut-out to protect the battery, and a fuse to protect wiring. The Maxim Integrated MAX8212 Micro-power Voltage Comparator with 1.15V reference switches a high side P-Channel MOSFET to disconnect the load. The MOSFET has a low on resistance of 4.1mOhms and a maximum current capability of 90 Amps well exceeding that of the battery. The …