Category: Device Bus

XPortHub3 w/Watchdog

I decided to start making some changes to the DeviceBus experiment. Basically I squeezed the function up in the right corner. Next I will replace RS232 with 2 x RS485 and add a LoRa or maybe Wifi and LoRa. I have little usage for Wired Ethernet on mobile devices, but I do lack radio options.

Device Bus – Part 5 Signals

This illustration show the 6 signals currenty used for “Device Bus”. The 3 first are a standard SPI in Half Duplex mode. That means that one device is Half Duplex Master driving the clock and sending on MOSI, while the others send/receive on MISO. The extra signals are designed to assist in deciding whom becomes…

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Device Bus – Part 1

I was in the middle of planning a 8 pin bit-bang bus as my attention was drawn to STM32G070KB that cost 0.7 USD, comes in a LQFP32 package and contains: 2 x 1Mbps I2C, 2 x 32Mbps SPI, 4 x 6Mbps USARTS, 128Kb Flash, 32KbSRAM, running at 64Mhz and 7 DMA channels. Looking at the…

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STM32 Flash Usage

STM32L011F4 only have 16Kb Flash, and as I generate the code I need from STM32CubeIDE it compiles to 11,37Kb on Debug, leaving only 4,63Kb Free for the application. Looking at the map I see several nasty C functions n the drivers. The GCC compiler is decently good and greedy on bytes, but that don’t help…

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This is the block diagram for XPortHub2 with an added Watchdog/D-bus. My objective here is that I want to add some features to the board and decided to do an experiment adding an external Watchdog/D-Bus by using a smaller STM32 in support. SPX3819 can be switched on/off enabling me to power a board on/off. Adding…

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