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…
I decided to change XPortHub2 due to parts of the layout – I need to use SPI 1 for “Device Bus” due to speed on F405, but the paths was crossed with Ethernet SPI and USB, meaning I had high frequency signals close without any isolation. I decided to re-route that part and add the…
I needed a board to test the new Device Bus/Watchdog so I stripped a XPortHub2 and added the logic that can be seen in the top right corner. It occupies almost 1/4 of the board so it does require some space. I need to work on that to find an optimal layout/solution. I am considering…
This is the schematics for Device-Bus, current sensor and power switch. I have a stripped down XPortHub that I might use for testing – removing W5500 leaves plenty of space without digging into 2nd side and 4 layer design. I simply would like to make some boards, put them in a stack and test for…
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…
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…
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…
3D model of XPortHub2. This contains an 10/100Mbps Ethernet with a standard RJ45 socket that replace TF Card, I2C and SPI on XPortHub1. New style SWD port. Raspberry PI Backbone with SPI and CAN. RTC with Battery holder on back. 8 x user leds. 2 x CAN ports. CAN1 is connected on Raspberry PI Connector…
J4 at right is the SWD connector. This can be reduced to 3 pins (SWCLK, SWDIO and GND), but it is wise to include Boot0, nRESET and 3.3V. I have painted SWCLK and SWDIO lanes in light red – those are the important ones that needs to be kept as short as possible. The only…
This pic is from the new XPortHub2 with Ethernet via W5500. The routing is close to being a single layer. The total number of passive components makes this occupy 1/3 of the board. The only challenge here is that HR911105A is a bit to tall for the next board in the stack – this…