Introduction
USBasp is an open-source low cost AVR In-System-Programming (ISP). On-line stores offer this programmer at a very low cost.
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| My DIY AVR ISP Adapter |
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| Sample of USBasp programmer on Ali Express |
Its programming header pin to AVR ISP pin on breadboard while
prototyping. For convenience we must make another ISP board that hold
AVR device for program uploading.
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| A 3D Visualization of AVR ISP socket for USBasp |
Designing for AVR ISP Socket
I have been using most of AVR ATMega series from 8 to 40-pin counts
DIP package in prototyping. One designed PCB could fit these AVR
devices.
Schematic Design
Circuit design software make this schematic design fast and reliable
with their rich of device libraries and detailed pins diagram.
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| Schematic Diagram |
System doesn’t have its own power supply. It’s driven from ISP header. The header is a male 10-pin IDC socket.
A crystal clock X1 is optionally added targeting any AVR device that fused with crystal oscillator.
A 45kHz oscillator block created by NE555 timer IC that can be switch
to XTAL1 pin of AVR device. It’s useful for AVR fuse recovery.
Circuit Design
Devices connection in schematic design creates a netlist that export
to PCB design step. Most of devices symbol in schematic design have
their own PCB footprint.
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| Printed Circuit Design View |
This design requires about 17 on-board component counts. Final design is
a double-sided PCB. However top layer made of around a dozen of copper
tracks.
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| Copper pattern of this circuit design |
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| Top copper layer mirror |
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| Components layer – mirror |
PCB Fabrication
This circuit design is no simple as there are a lot of component
counts, and their on-board interconnections. This double-sided PCB can
become a single-sided PCB by replacing top copper with wire jumpers.
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| Finished and fully tested PCB assembling at component side |
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| Copper side coated with clear acrylic vanish |
I made this printed circuit by hand using toner-transfer-method. PCB
fabrication, assembling, and testing was completed nearly one daytime.
Click here to download design file. For time saving and good quality of PCB we can order for PCB fabrication service. It’s more reliable and professional. We can preview this design using online using online Gerber view.
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| PCB panel view using online Gerber view at component side |
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| PCB panel view using online Gerber view at copper side |
Testing with USBasp Software
I tested this ISP adapter with USBasp programmer I made. I have only a little AVR chips for prototyping.
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| Detecting Atmega32 using USBasp |
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| Detecting Atmega8 using USBasp |
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