Sunday, February 3, 2019

Preparation for new OHS gateway.

There is almost all functionality in OHS gateway that I have wanted when I started, however I have internal need to carry on :). One thing, I would like to improve, is the crypto capabilities that can never be achieved on otherwise very nice ATmega1284P 8 bit MCU. It somehow led me to look further into another step that would be 16 or 32 bit MCU. There are many choices in therms of available MCUs and platforms. Maybe to stay on Arduino platform and choose some of the ARM Cortex available. But I have decided to stay with older brother of now used NilRTOS called ChibiOS/RT, since the "operating system" RTOS is maybe the most important for me.

ChibiOS can support variety of MCU including RaspberryPi and ATmega, but vast majority of supported MCU are STM32 families of many kinds. Looking at those mighty 32-bit ARM MCU, I have picked one called SMT32F407. These are high-performance Cortex-M4 32-bit RISC operating at a frequency of up to 168 MHz. They features a floating point unit (FPU), Ethernet, USB, RTC and so on. They have up to 1MB of flash storage and 128k of user usable RAM, and they are available in in various packages with varying pin count.

My goal is to create new gateway with similar functions as the current ATmega one, and then build up on this.The gateway may have different number of hardware zones, but I want to use wire and wireless nodes and zones. That is, I intend to still use Arduino based nodes s much as possible, just because of their easy to use nature. I plan to add GSM module on gateway, maybe as add-on board, so it can be swapped to 4G module in future. And also wireless radio, maybe as add-on board too. SMT32F407 has software defined TCP/IP stack, and it can be used with IPv6, Web Socket, SSL/TLS and so on. And what I like most, as ChibiOS supports many more even higher performance MCU, the future grow will be then much easier.

Saying all that I will continue to support, and develop new functionality on current ATmega gateway, as I use it at home :). The new one will not come anytime soon (this year), as it bring great deal of challenges in terms of HW and SW. Also I will keep the project open, as I do not like equipment that dies when its producer decides to cut it off, or just disable the required host server.