Microchip Technology AT SOIC14 Development Board
Specifications:
- Supports a variety of 14-pin SMD parts
- Programming options: ICSP or UPDI
- Programming support for various ATtiny models
- Optional external crystal (16MHz)
- Includes MOSFET, resistors, capacitors, and sockets
Product Usage Instructions
Board Details:
The AT SOIC14 development board is designed to support various 14-pin SMD parts with ICSP or UPDI programming options. Refer to the Board Details section for a list of compatible devices.
Parts List:
-
- U1: SOIC14 – Narrow ATtiny/tinyAVR
- X1: 16MHz Crystal (TH) – Optional
- Q1-Q10: MOSFET A2SHB/SI2302 SOT23 SMD
- R1,2,4-11: 470 Ohm 0805 SMD/TH Resistor for transistor drivers
Assembly Guide:
Proper assembly is crucial to prevent damage to ESD sensitive parts. Use proper ESD protection and soldering equipment during assembly. Smallest components like 0805 resistors can be hand soldered with care using a fine tip soldering iron and appropriate flux.
Programming:
The board supports ICSP/SPI programming for ATtiny 24, 44, 84, 441, 841 with an external crystal option. For devices that support UPDI pin 10 programming without external crystal, refer to the list in the manual.
Optional Components:
Optional components like the 16MHz crystal and additional capacitors can be used based on the specific requirements of the connected devices.
FAQ:
- Q: What should I do if I encounter issues during programming?
A: Ensure proper connections, check the programming voltage levels, and refer to the device datasheets for programming specifications.
Description
Front
Back 
The AT SOIC14 development board supports a variety of 14 pin SMD parts with ICSP or UPDI programming options (See the Board Details for a list of devices). Generally, those parts in a SOIC14 narrow package with VDD at pin 1, GND at Pin 14, and UPDI on pin 10 or ICSP should work.
Connections to all IO pins are provided (Referenced P2-P13) as well as a sub set of connections through SMD resistors and MOSFET drivers. A total of 10 MOSFET transistors are available or optionally a bipolar junction transistor (BJT) can be used. The only outputs that do not have a transistor option are Pins 2 & 3. See the IO Pin Connection Planning Guide at the end of this document for details.
A dedicated power connection is provided (PW) and other connection areas are marked as power (V+) and ground (GND) for sourcing other components. The power supply range is determined by the selection of U1, typically 2.7-5.5 volts.
Programming can be accomplished using the In-Circuit Serial Programming (ICSP) port to program the mounted part on the board. There is a jumper option to select either ICSP or UPDI mode. I also have available soft touch programming cables for either mode (No ICSP socket needed). There are many YouTube videos on Arduino programming options.
This board was designed to be as small as possible while providing numerous connection options and a set of MOSFET drivers for LED lighting in scale model builds. Typically used in scale model builds, dioramas or other areas where a small compact SoC (System on a chip) is needed.
Board Details
- Dimensions: 34.3 x 26.7 mm
- Parts Supported: VDD pin 1, GND pin 14. Designed for the ATtiny 24/84 series but supports others.
- ICSP/SPI Programming (External crystal option):
- ATtiny 24, 44, 84, 441, 841
- UPDI pin 10 Programming (No external crystal support):
- ATtiny (tinyAVR Series-2) 424, 824, 1624, 3224
- ATtiny (tinyAVR Series-0) 1604, 804, 404, 204
- ATtiny (tinyAVR Series-1) 1614, 814, 414, 214
- Up to 10 MOSFET or BJT drivers supported, see the IO Pin Connection Planning Guide at the end of this document for the 10 fixed outputs.
- Programming using the ICSP/UPDI port.
Parts List
| Part Reference | Quantity | Value | Description | Source Links |
| U1 | 1 | SOIC14 – Narrow ATtiny/tinyAVR | Mouser Electronics https://www.mouser.com/c/semicon ductors/embedded-processors- controllers/microcontrollers-mcu/8- bit-microcontrollers- mcu/?q=ATtiny&package%20%2F% 20case=SOIC-14%7C~SOIC- Narrow-14&instock=y | |
| X1 | 1 | 16Mhz Crystal (TH)
|
Mouser Electronics https://www.mouser.com/ProductDetail/ ABRACON/ABL-16.000MHz- B4Y?qs=sGAEpiMZZMsBj6bBr9Q9acs m1aZFaUGXsH5khlLoENx8BbElI4UD1 w%3D%3D | |
| Q1- Q10 | 10 | A2SHB | MOSFET A2SHB/SI2302 SOT23 SMD | Mouser Electronics https://www.mouser.com/ProductDetail/ Vishay-Semiconductors/SI2302CDS-T1- E3?qs=%252BPu8jn5UVnHNrjAmGCs %2Fuw%3D%3D
AliExpress |
| R1,2,4-11 | 10 | 470Ω | 0805 SMD/TH Resistor for transistor drivers | Mouser Electronics https://www.mouser.com/ProductDetail/ Vishay-Draloric/RCG0805470RJNEA?qs=vOeJ qewp7jBU33bjXc%252BrVQ%3D%3D |
| Part Reference |
Quantity |
Value |
Description |
Source Links |
|
R3 |
1 |
10kΩ |
0805 SMD
|
Mouser Electronics |
| C4 | 1 | 1uf | 0805 SMD Decoupling cap | Mouser Electronics https://www.mouser.com/c/passive- components/capacitors/ceramic- capacitors/mlccs-multilayer-ceramic- capacitors/multilayer-ceramic- capacitors-mlcc-smd- smt/q=0805%20capacitor&capacitance =22%20pF%7C~0.1%20uF%7C~1%20 uF&instock=y |
|
C1 |
1 |
0.1uf |
0805 SMD Decoupling cap |
Mouser Electronics |
| C2,C3 |
2 |
22pf |
0805 SMD
|
Mouser Electronics |
| ICSP | 1 | 2×3 | 2×3 pin socket 2.54 mm pitch
|
Male/Female socket header based on programming needs. |
| PCB |
1 |
AT SOCI14 Dev Board |
Pre-Assembled Boards
If you purchased an assembled PCB your board will be assembled based on the option you selected:
- Option 1/2: Board assembly with
- ATtiny841 or ATtiny3224
- All decoupling capacitors
- This option will include all 10 MOSFETS loaded with their corresponding 470Ω resistors.
- Parts listed as OPTIONAL will NOT be loaded (ICSP/PW Header, Crystal, C2, C3, R3).
- To test the board a test program will be loaded to U1 and used to check all output pins. It is a simple high/low test pattern applied to each pin about every ¼ second or so.
- You should be able to power up your board and see that same test pattern if your selection included U1. I’d recommend doing this before you reprogram the part in case something happened in transit.
- See the Board Options/Configuration section for configuring MOSFET outputs.
Assembly Guide
Caution: Electrostatic discharge (ESD) is a sudden and momentary flow of electric current between two differently-charged objects when brought close together or when the dielectric between them breaks down, often creating a visible spark associated with the static electricity between the objects. 1
This type of shock can cause damage to ESD sensitive parts such as those used in this build especially U1. Proper ESD protection and soldering equipment should be used to prevent damage to parts during assembly and implementation into your project.
Assembly Planning
The smallest components are 0805 and while small can still be hand soldered with care and patience. A fine tip soldering iron is useful along with 0.015” (0.38mm) flux core solder and extra flux if needed. See the references section for a YouTube video link on assembling this and other boards.
A note on connector sockets: The ICSP and PW locations support 2.54mm pitch sockets. However, I have found that these can cause a height issue with scale models as space can be very limited. For flexibility I usually wire directly to the board or use in-line connectors to keep the board height to a minimum. An angled 2×3 header for the ICSP can be better than a vertical one or the use of a soft touch programmer cable eliminates the need altogether.
PCB Assembly
- PCB assembly can be completed in any order.
- If using a hot plate or reflow heater I usually start with the side with the most SMD or hardest parts to hand solder and then hand solder the other side.
- If you are completely hand soldering my recommendation is to complete the back of the board first by mounting the capacitors C2,3,4.
- Next determine if you will use the reset pull up resistor R3. The reset pin has a weak internal pull up but a stronger one may be desired.
- If using the external crystal install capacitors C4,5.
- Next install any transistor output drivers for LED’s or other needs. Depending on your design of input and output signals you may not want to mount all of the MOSFET or BJT parts and the associated resistors. I’ve included a design planning table at the end of this document that can be used to help lay out your design and connection options.
- Continue to mount the 470Ω SMD (or a value of your choice in SMD or TH) resistors for each transistor installed.
- Moving to the top of the board install U1 and C1.
- Repeat the mounting of any other resistor/transistor pairs for the top layer.
- A note about MOSFET transistors. To keep the board size as small as possible I did not include any gate pull down resistors. These are usually used to prevent signal instability when U1 initializes the output pins on power up. If you feel these are needed for your design an appropriate value resistor can be added across the
gate/source pins of the MOSFET. They are generally not needed when using BJT transistors. - If using X1 install the crystal.
It can be useful to bend the crystal pins to hold the part in place for soldering. Once one pin is soldered check that the part is flush with the board. If not just reheat the connection while pressing the part flush with the board. You can then solder the remaining pin. - Determine how you will program the part and if needed install a 2×3 (2.54mm pitch) header for ICSP.
- If you will be using a connector for power then install a 1×2 (2.54mm pitch) header at PW.
- 1 Definition provided by From Wikipedia, the free encyclopedia. For more information on ESD see https://en.wikipedia.org/wiki/Electrostatic_discharge
Board Options/Configuration
This section should be reviewed for those that are assembling the board themselves or purchased a pre-assembled version. Using the table below determine which programming method will be used. Selecting ICSP (JP1, 1 & 2) will connect the MISO line to ICSP pin 1. Selecting UPDI (JP1, 2 & 3) will connect the UPDI pin 10 to ICSP pin 1. When using UPDI only pins 1, 2, and 6 will be used on the ICSP header.
Jumper Options
| JP1 | 1-2 – ICSP 2-3 – UPDI |
Solder jumper selecting UPDI programming option
Making a solder bridge
You can make your connection by selecting which half of the bridge to connect but make sure you do not connect both parts. The center pad will connect to either the upper or lower pad, ie pad 1-2 or 2-3. Once you determine the pads to connect add some solder to each pad then continue to heat both pads adding more solder if needed until the two pads are connected. The images below show some examples:
IO Connections
| Power | PW +/- Connect an appropriate power source to the PW connector. There are also extra power and ground connections for other needs. (V+ / GND) |
| Reset | P4 The reset can be used as an input and depending on your design you may want to remove or change the R3 pull up resistor. Use care if setting this port as an output as this is one of the programming pins and cannot easily be reverted back to be a Reset. (ATtiny84, 841 series only) |
| ICSP | Programming connection for a serial programmer to program U1 on the board. Supports ICSP/UPDI modes |
| IO Ports | Round Pads
P2/3 These connections are IO only and do not have transistors to drive a load. |
| Transistor Outputs | Square Pads P4-13 These connections align with the devices port outputs and have a resistor/transistor to drive a load. The transistors (MOSFET/BJT) sink to ground. P4 or P10 will align to a reset pin depending on the device selected. See IO Pad Sections below for examples. |
| Development Areas | This board used some available free space as a development area for adding other components (Resistors, transistors, diodes, sensors, connectors, etc…). |
IO Pad Sections
Each grouping of IO ports has two connection options.
- IO Port Output – Connect to the port IO output directly (Round Pad – No resistor or transistor driver)
- Transistor Output – Connect to the transistor output driven by this port (Square Pad)
ICSP/UPDI Header
The ICSP connector follows this layout which is the same used for Arduino boards. There are a number of YouTube videos showing various methods for programming including using UNO or Nano boards as an AVR In System Programmer using the ArduinoISP sketch.
Note in UPDI mode the MISO pin connects to the UPDI (pin 10) of the device.
I also offer a soft touch programming cable to eliminate the ICSP header and connect directly to the board. Cable versions are available for ICSP or UPDI.
Mounting Options
Hot glue is my go-to option for PCB mounting in models. It has great hold and sets up quickly. It can easily be removed and reapplied. Double sided tape or possibly Velcro could also be used.
References
- Github: Development board documentation and schematics.
- YouTube: Board assembly and project videos that are related to this board.
- SerialUPDI
- Arduino IDE board files
- megaTinyCore – https://github.com/SpenceKonde/megaTinyCore
- It can be installed manually or through the Boards Manager
Revisions
| R1 | First release |
Disclaimer
This information is provided “as-is” with no representation or warranty of any kind whether express or implied. However, I’ve tried to make this document (as well as the supporting videos) as useful and accurate as possible. If you find something that is incorrect or confusing, please let me know as I would like to make the correction so others will not have the same issue.
Feel free to email me for issues you may have with this board or if you need extra help with coding, programming, or just design ideas for your latest project please check out my Patreon page. johnnyelectronic1@gmail.com
Legal note
Microchip, AVR, tinyAVR, megaAVR, ICSP, and In-Circuit Serial Programming, are names of Microchip, it’s products and product lines, and as such are all trademarks of Microchip.
IO Pin Connection Planning Guide
Use this guide to help plan out your inputs/outputs/LED driver connections. It has helped me during planning and final assembly.
ATtiny SOIC14
- Actual IO lines will depend on the device selected.
- RED Sections: Pin 2,3, No transistor option.
- When directly driving an output (No MOSFET/BJT) there is a 20ma max per pin and a 100ma total for all pins or per device.
- MOSFET’s can handle a few 100 mA without issue, the ones selected are rated to over 2 Amps but watch for excessive heat.
| CONNECTED TO WHAT? N/A – VDD |
INPUT/OUTPUT PINS/PORTS
1 |
14 |
CONNECTED TO WHAT? N/A – GND |
||
| 2 (P2) | 13 (P13) Q7 | ||||
| 3 (P3) | 12 (P12) Q6 | ||||
| 4 (P4) Q2 | 11 (P11) Q8 | ||||
| 5 (P5) Q1 | 10 (P10) Q9 | ||||
| 6 (P6) Q5 | 9 (P9) Q10 | ||||
| 7 (P7) Q3 | 8 (P8) Q4 | ||||
Documents / Resources
 |
Microchip Technology AT SOIC14 Development Board [pdf] User Guide AT SOIC14 Development Board, AT SOIC14, Development Board, Board |
