HardLabs

Freifunk open mppt

elektra42·freifunk-open-mppt·Schematic-and-Board/MP-Tracker.kicad_pcb

Freifunk open mppt PCB layout, top view — open source AVR/Arduino board by elektra42

About the Freifunk open mppt PCB

Freifunk open mppt is an open source AVR/Arduino PCB design by elektra42, published on GitHub under the Custom license license. It is a 2-layer board, with 61 components from 36 distinct parts.

Its main chip is the ATMEGA8, from the AVR/Arduino family. Other key parts include the MC34063, TL081 and MC78L033. By type, the board carries 25 resistors, 17 capacitors, 6 diodes, 4 ICs, 4 transistors and 2 connectors.

It belongs with the power & battery designs in this gallery.

From the project

Open hard- and software solar maximum power point tracker

These are preliminary sources and CAD files from the Freifunk-Open-MPP-Tracker project.

At the moment, the buck converter section is based on the el cheapo and low-fi MC33063 controller chip. It can easily be replaced by a faster and more fancy switch converter IC to construct a more powerful and slightly more efficient buck converter section. However, with the external powerful P-MOS switches, the efficiency was already around 94% with the first prototype (measured at 2 Ampere output current).

Main components on the Freifunk open mppt

MC34063TL081ATMEGA8MC78L033

Freifunk open mppt bill of materials (BOM)

61 components, 36 distinct parts.

QtyPartRefs
1
MC34063
U1
1
TL081
U2
1
ATMEGA8
U3
1
MC78L033
U4
2
BC817-40
Q1, Q3
2
IRFR5303
Q2, Q4
1
3.6864MHz
X1
1
—
P1
1
TEMP_SENS
P2
1
1N4148
D1
3
1N4001
D2, D7, D9
1
6V2
D4
1
DIODESCH
D5
1
27u
L1
1
—
L2
6
470n
C1, C2, C3, C7, C10, C12
2
15p
C4, C5
2
330u
C6, C14
1
68p
C8
2
100n
C9, C11
Show 16 more
QtyPartRefs
1
1000u
C13
3
470n
C16, C17, C18
7
1k
R1, R4, R7, R10, R25, R31, R32
1
4K7
R2
1
470R
R3
3
10k
R5, R13, R19
1
47R
R6
2
27k
R8, R20
3
3k3
R9, R12, R27
1
22k
R11
1
33k
R14
1
15k
R15
1
6k8
R16
1
2k35
R21
1
47
R22
1
15k
R26

Freifunk open mppt design files

The KiCad project lives in the elektra42/freifunk-open-mppt repository on GitHub; these links point at the commit this page was built from.

Freifunk open mppt: common questions

What microcontroller does the Freifunk open mppt use?

The Freifunk open mppt is built around the ATMEGA8, from the AVR/Arduino family.

How big is the Freifunk open mppt PCB?

The Freifunk open mppt has 2 copper layers and is 1.6 mm thick.

How many components are on the Freifunk open mppt?

61 components, from 36 distinct parts. The full bill of materials is listed on this page.

Where can I download the Freifunk open mppt design files?

From the elektra42/freifunk-open-mppt repository on GitHub, which has the KiCad layout; the links under Design files point to each one.

Can I use the Freifunk open mppt design in my own project?

It is published under Custom license, which limits how it may be reused; read the license before building on it.

Can I test firmware for the Freifunk open mppt without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug AVR/Arduino firmware against it before you order a PCB.

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