• First prototype

    electrobob05/23/2017 at 20:05 0 comments
  • Which radio?

    electrobob05/23/2017 at 20:04 0 comments

    The radio used to transmit the data between nodes is one of the crucial parts of the system. As mentioned in the Lessons learned, the NRF23L01 or RFM75 was a good candidate, but eventually failed to meet the needs, so I chose the RFM69. Truth be told, I believe the perfect radio is a combination between the two and some bonuses.

    More info at http://www.electrobob.com/1000-1000-hardware/

  • Which microcontroller?

    electrobob05/23/2017 at 20:01 0 comments

    Which microcontroller?

    When I began this project, I was long given up on the ATMega and ATTtiny micro, with some exceptions, as they are not really justified in a hobby environment. Therefore, I have initially intended to make my nodes using an ATXMEGA32E5, which I believe is an ideal device for sensor nodes, due to the various and low power peripherals. However, it soon turned out that for some devices I would need more flash, but the family stops at 32K and a package change is required for more memory. So I dropped it in favour of the new SAMD21, ARM cortex M0, which comes with more flexible package and flash options. This device burns a little bit more in sleep, but still tolerable. And a 128K flash and 16K RAM version costs on par with the lousy old atmega328 with tons of extra features (way better ADC, DAC, more PWM, more timers, more I/O, more flash, more RAM, faster core, lower uA/MHz, RTC, more SPI, mor UART, more I2C….i’ll stop here).

    More info at http://www.electrobob.com/1000-1000-hardware/