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11/15 Signal Processing ## Week 10: In this week, we learned how to ... # Class notes - The gate resistor is used to slow down the signal to the mosfet. Networking and Communications - modularity - Wired Networks - asychcronous vs synchronous: synchronous serial is preferred, because it is clocked. - SPI, used by SD memory cards to read an write lines of data. - I2C, a lot of sensors use I2C to communicate - Wireless Networks - Single Chip Radio - Antennas: the shape of the Antenna create impedance - WiFi: Xiao serves a webpage and handles local requests, collaborative multitasking (loop is stoped with async) - Bluetooth: have profiles, NUS (bluetooth profile from Nordic using UART), How - WebBluetooth: Serial port through the air - RFID: Read and Write recoginized with coil - LoRa: city scale, agricultural Networking - software radio - Send Data optically, rgb light Show and Tell --- ## Idea - Continue last week's experimentations and add network interface. # Assignment - individual assignment: design, build, and connect wired or wireless node(s) with network or bus addresses and a local interface - group assignment: send a message between two projects # 1) PCB for LIG x LCE Continuing last week's progress, I trouble shooted the pcb board that switches the 12v power supply. Two things I changed: - break out all the pin of the Xiao ESP32C3. For my previous pcb board, I only broke out one pin of the ESP. That made trouble shooting very unflexible. - remove the gate resistor and made the flyback diode optional. Just to further remove sources that could cause trouble. I then designed and milled the boards.    Trouble shoot conclusion: - Mill the holes of blue prints using 1/32. - check the direction of power jack. I had the plug in face facing inward. - Desoldering components with more than 2 legs, it's better to use a hot air to heat up the whole area. - **When connecting several boards, break out GND on each board so that they can connect to a common GND** I had to add a wire post milling.  I tested all connections, however, it was still not working. I looked up the [datasheet](https://www.mouser.com/datasheet/2/916/PMV45EN2-1319180.pdf) of the mosfet I used and realised it has a **Vgs of 10v.** I switched the mosfet to a [SI2336DS-T1-GE3](https://www.digikey.com/en/products/detail/vishay-siliconix/SI2336DS-T1-GE3/3748946) and the board worked. # 2) ESP32 Web Server With a functioning esp32 switching 12v, I started to work on controling GPIO pin with a web server. This was the [tutorial](https://randomnerdtutorials.com/esp32-esp8266-web-server-physical-button/) I followed and it worked right away. - remember to connect all devices to the same network. With everything set, I connected the components: ESP32 hosting a Web Server, mosfet board, 12v power supply, LIGxLCE sheet. ## Next Steps - use copper plating to make heating frame --- # Resources - files - [wifi btn code](files/wifi_btn.ino) - Buy your own 1/64 and 1/32 End mills. --- ↳About