IoT device to check if doors and windows are closed or open https://cgit.xengineering.eu/iot-contact/atom?h=main 2025-08-10T15:36:15Z 2025-08-10T15:36:15Z xengineering me@xengineering.eu 2025-08-10T15:36:15Z urn:sha1:c50d7275a98c420506c1be35d1c067394af700f5 They should be used to easier connect cables to the board to debug hardware or firmware issues. 2025-08-10T15:28:31Z xengineering me@xengineering.eu 2025-08-10T15:28:31Z urn:sha1:69ac0e4b43d0c48cca58008d41d4551bb723d510 2025-08-10T14:38:52Z xengineering me@xengineering.eu 2025-08-10T14:38:52Z urn:sha1:a7ce8945983816c77b9d0b40e9619857b6721065 2025-07-29T09:52:27Z xengineering me@xengineering.eu 2025-07-29T09:52:27Z urn:sha1:939abbffbb0d1f120df017a6984f4a24af8c86da Adding this TODO text and marking the termination and shielding related pins as unconnected makes the ERC clean. This allows to right now fail the build in case of bad ERC. This is preferred to not unintentionally inject other issues. The RJ45 connector and shielding / termination has to be reworked anyway. 2025-07-27T16:01:47Z xengineering me@xengineering.eu 2025-07-27T16:01:47Z urn:sha1:514352748fee605be176e2f37dd9b12047458503 ERC brought up that those two global power labels were mixed. This is of course a design bug which is now fixed by consistently using +3.3V. 2025-07-27T15:43:05Z xengineering me@xengineering.eu 2025-07-27T15:43:05Z urn:sha1:95ecbd8c555d3021a08bedb4234f38abd0df2db3 The old concept was to have three connectors: - 2-pin for contact loop - 3-pin for AC supply (PE, N, L) - 4-pin for blind connection (PE, N, L_UP, L_DOWN) The new concept is: - 2-pin for contact loop - 3-pin for AC supply (L) and blind connection (L_UP, L_DOWN) This saves the PCB space for one of the biggest parts. Furthermore it reduces space constraints for the PCB routing. The removed neutral and protective earth pins should not be a problem. It is less convenient for mounting since additional connectors between the supply and blind cable are required but apart from that N and PE would not have safety benefits in the current design. This used to be different when an aluminium case was considered at least as option. But the requirements for PE connection of the two halves of the housing would have a huge space requirement. Thus an anyway cheaper plastic case is the current goal. 2025-07-25T20:25:27Z xengineering me@xengineering.eu 2025-07-25T20:02:41Z urn:sha1:d3e7f19f1f87b03e9a7c8a170b9c4351ac565268 This resolves ERC issues. The ERC complains that an power input is not fed by a power output if there is a component like a ferrite bead or 0 Ohm resistor between the two. The `PWR_FLAG` tells the ERC that it was explicitly checked that this is not a mistake. 2025-07-25T19:49:35Z xengineering me@xengineering.eu 2025-07-25T19:49:35Z urn:sha1:0937bceda70b14f9ac66f58954eb4dc91bc15068 2025-07-25T16:52:35Z xengineering me@xengineering.eu 2025-07-25T16:44:28Z urn:sha1:a5c810a52c6157648f234edac6654fff325d0765 2025-07-25T16:35:13Z xengineering me@xengineering.eu 2025-07-25T16:35:13Z urn:sha1:00410764a9c6c13eea872b029a6055a9e6cc5d3f The internal pull-up resistor of the STM32 can be used. 2025-07-25T16:21:10Z xengineering me@xengineering.eu 2025-07-25T16:21:10Z urn:sha1:68d56b6f8e1abeaaa6982245bb73e9f9d712b44c 2025-07-25T15:28:27Z xengineering me@xengineering.eu 2025-07-25T15:28:27Z urn:sha1:4a86aafe5d6ad1f16381ed339b3ec641239be3e2 It is hard to say if these are necessary. For sure they are not necessary anymore when the device is assembled inside the case. Thus the risk is taken to provide some more space and reduce assembly effort. 2025-07-24T20:51:23Z xengineering me@xengineering.eu 2025-07-24T20:51:23Z urn:sha1:360bc81c7532b6677dfb01898bbd94eca6ab75d2 The idea of the red LED used to be to indicate power delivery to the board independent of firmware. While this is good to know it adds the constraint that even without firmware the LED should light up. Furthermore it should stop lighting up when the firmware takes over the blinking with different colors. This was solved with a NOT gate. This adds more parts to the assembly at the cost of rare space. To reduce space consumption this feature is removed. The effect is that the user cannot distinguish anymore if the board has an issue with power supply or with not running firmware. This is acceptable because the user cannot do anything about both issues. Developers have the chance to e.g. connect the UART to validate if the firmware is running. 2025-07-24T20:46:30Z xengineering me@xengineering.eu 2025-07-24T20:43:11Z urn:sha1:abfefc7f1bc9927f99e38bb89762dbd6a19ed460 It is required to save as much place as possible on the PCB. There used to be these reset methods: - JTAG reset - button reset - power-cycle - firmware-based reset Taking away the button reset option is reasonable since for the development and production use case there are still enough options. Developers should use the JTAG reset or power-cycle and users will anyway use firmware-based resets (e.g. during updates) or power-cycles which is anyway most intuitive to users. 2025-07-24T20:40:21Z xengineering me@xengineering.eu 2025-07-24T20:40:21Z urn:sha1:19daf5941c95a34eb6596e4a62de541a6080f644 Now there are 6 locations for 3 zero Ohm resistors. Three places to power by PoE and three to power externally. Never all of them should be placed. 2025-07-24T20:18:49Z xengineering me@xengineering.eu 2025-07-24T20:18:49Z urn:sha1:944c834a7dabf5335c0780e14348b1d7d65ebe9c 2025-07-24T12:45:32Z xengineering me@xengineering.eu 2025-07-23T12:00:31Z urn:sha1:5e15c86cd5197466653f510a7ccc4b76d67f69d1 2025-07-23T11:10:34Z xengineering me@xengineering.eu 2025-07-23T11:10:34Z urn:sha1:efe675df60a05ca7a8140788f99e0647d22b1071 The status LED should always display on color either constantly on or blinking. To make sure even without firmware this is given a NOT gate is added. 2025-07-23T10:59:03Z xengineering me@xengineering.eu 2025-07-23T10:59:03Z urn:sha1:1e3c106c2d345aaff83f1db9a9a831f6dcbe8505 This is more space efficient and makes it easier to label the LEDs. There is just one "status LED" lighting up in different colors compared to one "update LED", "power LED" and "activity LED". 2025-07-23T10:31:40Z xengineering me@xengineering.eu 2025-07-23T10:06:45Z urn:sha1:63cc1ee45125c3d10f6c66d681bb59898a790691 2025-07-23T09:57:32Z xengineering me@xengineering.eu 2025-07-23T09:57:32Z urn:sha1:24d9a38a95a7cc51528efebcb5d81dd8ea67bef8 2025-07-22T16:40:02Z xengineering me@xengineering.eu 2025-07-22T16:31:07Z urn:sha1:52f6f99757e43f1ad5b551dee4c308c72c2a4cf5 2025-07-22T16:18:19Z xengineering me@xengineering.eu 2025-05-25T19:58:15Z urn:sha1:1620d188cfdc9660c69ab50b33d9e69ad99c34ea 2025-05-25T18:08:39Z xengineering me@xengineering.eu 2025-05-24T20:00:19Z urn:sha1:161dd48aa8a14bb99a31e91480977e2961d27a72 2025-05-24T12:04:13Z xengineering me@xengineering.eu 2025-05-24T12:04:13Z urn:sha1:5e48ef91e68fcddc591950ca56c930c50912454f Making them active-low makes it easier to reset the MCU. For the wipe functionality it does not make a role since it will simply be defined in Devicetree. 2025-05-24T11:52:16Z xengineering me@xengineering.eu 2025-05-24T11:52:16Z urn:sha1:6db34475d1935f368bec60f530f88cd066924849 This voltage divider provides an analog voltage between GND and +3.3V to indicate which hardware revision this board is. Thus the same firmware image can be used on multiple PCB versions compensating the hardware differences in software. The resistor combinations are calculated by `tools/resistory_selector.py`. 2025-05-24T10:01:55Z xengineering me@xengineering.eu 2025-04-11T18:22:05Z urn:sha1:fdd5234c383f294d934da0901f3bf7a96f2c19a3 This reduces the electrical contacts which is possible and necessary because of size constraints. 2025-04-01T16:13:10Z xengineering me@xengineering.eu 2025-04-01T16:13:10Z urn:sha1:aa3a6384f14ee7d148b84523aa30723bc1020d39 2025-02-18T18:44:49Z xengineering me@xengineering.eu 2025-02-18T18:44:49Z urn:sha1:968d182429594578654a983d8a5b605f8f152650 2025-02-18T18:26:05Z xengineering me@xengineering.eu 2025-02-18T18:26:05Z urn:sha1:19008e463bbf182e481e06c034299268fa329843 This makes it easier to keep the descriptions and the text inside the schematic in sync.