AtomDev-SAMD21 & Port-A-Proggy V2 PCB

V1 of the Port-A-Proggy had a Dual Micro or USB C but has some tiny headers that doesnt allow me to fully have fun. So i changed it up to larger strong headers that wont disconnect when in my hand or be to hard to make a cable for also.

The PCBs were designed by me and created by PCBWAY. They were also soldered by myself here at home. PCBWAY is pretty awesome. The creation was quick , the shipping was handled by DHL. Tracking anything coming from over seas to USA is always a hassle so I cant really complain there.

AtomDev – SAMD21-C is an awesome average sized PCB. The board is smaller than you think coming in at 1.7 x 2.22 inches or 43.2 x 56.3 mm. About half the average credit card size. This board is as basic as it gets. The MCU chosen was the Atmel ATSAMD21G18A-U. The board comes with all the basic circuitry like caps for power pins and crystal. (32.768khz) which gets bumped up via PLL to 48MHz.

It has a USB C connector meant for USB 2 spec. The board can be programed via Arduino IDE or UF2 drag and drop files. The Power supply uses the APK2112-3.3v which is a norm in most of my projects as it can supply 500mA easy and needs minimal parts. Seems to work great with USB devices. USB is fused via a 500mA resettable fuse. The board includes a Reset button and Power LED (Green). The Power LED connection can be unsoldered via a jumper on bottom of PCB to allow power saving.

On the lower portion of the PCB the user has a Button and LED for any use. As the Silk Screen states the User Button is connected to PA06 and the User LED is connected to PA07. Both can be disconnected from those pin by unsoldering the jumpers on the bottom of the PCB. This allow for other use with out interference.

All pin headers are clearly labeled. Vin is also 5V from USB and is brought out on both sides of PCB. On each corner is a GND pin and 1 3.3v pin on the bottom left. There is also a POGO header in the top mid/left of the PCB for quick programming using a tag-connect type header.

This is the bottom of the PCB, as you can see there are 4 Solder Jumpers. User LED, Button and Power LED along side of USB_CHECK which connects a Resistor Divider to PA14 if soldered.

That’s about it for the SAMD21-C on this post, now onto the Port-A-Proggy..

I know such a weird name. Its name comes from its original use… as a Portable Programmer. I initially designed it to be used as a on the go programmer for AVR SPI devices. Like the ATMEGA328P that’s in the notorious Arduino Uno, but I have since put the project on hold as I needed to get back to normal work life.

The Port-A-Proggy has a 2.7in Sharp Memory LCD and 4 buttons on the front. The buttons are using only 1 analog pin by using a resistor divider. This saves on pins.

On the back of the PCB is where all the magic happens. To lower cost ive decided to leave out the USB to UART IC and have a separate programmer which is simple enough and cheaper to have one over one on every PCB.

On the Top Left you can see the ESP32-WROVER-E with 8MB. ESP32 is an amazingly fast MCU with Dual processors and Bluetooth/Wifi. I decided to use the module because it contain everything needed already such as antenna and memory with passives. Makes life simpler.

The board can be powered via USB C cable or Lipo Battery. The power supply ive used here is the TPS62132 which is a 3A Step-Down Converter In 3-mm × 3-mm QFN Package, locked in at 3.3v. Its one of my favorites as the input voltage range is from 3v to 17v. So Lipo, USB , 12v brick… all can be used with it.

Also included is a 5v boost using the TPS613222ADBVR which is a 1.8-A Switch Current Boost Converter. It’s used for the Sharp Mem. LCD as it requires 5v for power but uses 3.3v Logic. I did not test if the LCD will from LIPO without the boost, so not sure if this was needed. I recommend it as its what’s needed per datasheet of LCD. U$5 is a SS8P3C, High Current Density Surface-Mount Dual Common Cathode Schottky Rectifier. This allows me to combine 2 power rails without them touching each other really.

The LIPO can be charge via USB C connector using the onboard MCP73831 IC.

The MicroSD Connector along with most of parts on board are nicely labeled so you don’t have to look at documentation all the time to figure something out.

There are 2 huge headers that have lock-in housings. I chose these for V2 because it allows for larger wires and less likely for a cable to disconnect when using it in your hand. The header marked ICSP is for programming but can also be used as a UART port.

The Header marked Target SPI can be used for SPI or I2C or GPIO. The last things to mention on this PCB are the On/Off switch and the SMT Pads. The switch is a normal slide switch capable of 600mA and the SMT pads allow for any … extra testing or GPIO needed for task.

The quality of the PCBs were great! No broken traces. Silk was nice and clean even at such small sizes. I haven’t had any issue with these yet and I dont suspect any. I will definitely use PCBWAY again for some boards.

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