USB Host mini in test fixture
The first batch of USB Host Minis is built, tested, and boards are available in store. It is designed to be employed in lightweight, battery-operated circuits, for example, used for digital camera control. It can also be used as general MAX3421E breakout board. Title picture shows the board proudly sitting in its’ own ghetto-style Sparkfun-inspired pogo bed.
The design follows Arduino Mini minimalistic approach. It is 3.3V only and mates quite nicely with Sparkfun 3.3V Arduino Pro Mini. Only essential control and GPIO signals are available – no power supplies, level converters, or even jumpers are provided due to lack of space. However, since rearranging control signals is often necessary, extra pads have been placed for this purpose. They can be seen on product picture at the top and to the left of MAX3421E IC.
The board has VBUS routed to 3.3V. Even though the voltage is lower than specified 5V, the shield has been tested to work flawlessly with numerous self-powered devices, such as digital cameras, as well as some bus-powered devices, such as Sandisk Cruzer flash drive. However, if 5V VBUS is necessary, board can be easily modified – the trace from 3.3V to VBUS can be cut and 5V applied using a pad placed on the board for this purpose. It can be arranged using single 5V supply; since Arduino Pro Mini has on-board LDO, 5V can be applied to VRAW and VBUS while shield will be getting its’ 3.3V power from Arduino board, as usual.
Bottom picture shows my favourite arrangement – Arduino Pro Mini sits on top of the shield with its’ programming connector easily accessible from either side. Also, Arduino reset switch is easily accessible this way.
Project files and schematic are available in Downloads section. If you have any questions about this design, e-mail me or leave a comment here.
USB Host Mini and Arduino Pro Mini
First prototype of USB Host Mini
This is the status update on Arduino USB Host Mini development, announced 3 weeks ago. I received rev.0 PCBs last Saturday – BatchPCB is faster than ever! I made a test build (see title picture) and after fixing one major and several minor mistakes placed an order for what I’m hoping will be the final pre-production sample.
The prototype was built to sit on top of Arduino Pro Mini to make access to the parts easier during troubleshooting. On the final board USB connector is placed slightly further away from the pins; it will be possible to place Arduino on top of the shield so that the height of the “sandwich” will be less or equal to the height of USB connector.
In 2-3 weeks I’m hoping to finalize the design and start producing the USB Host Mini. Stay tuned!
USB Host mini rev.0
This post announces starting of development of new Arduino USB Host Shield variant. There are several projects in the works (thanks, guys for letting me know!), where standard size Arduino board is too big. Since electronics of USB Host Shield is pretty simple, it was decided to shrink the board as much as possible. Here is the first iteration.
The initial revision of USB Host Shield in Mini form factor is shown on title picture, It is intended to be used with Sparkfun’s 3.3V Arduino Pro Mini. Intended applications include digital camera control devices, robots, as well as any other projects where size and weight has to be minimized. The Gerbers was sent to BatchPCB; I’m expecting boards back in couple of weeks. The main goals of this first prototype are manufacturability check as well as checking claims made below.
The Mini Host is simplified version of full-sized shield; only USB and GPIO are available. By default, VBUS is routed to VCC, therefore only self-powered USB devices are expected to function (even though I have at least one USB flash drive which works fine powered from 3.3V VBUS). I also provided extra pads to simplify signal re-routing, however, since there was no place left for jumpers a trace has to be cut instead. The same has been arranged for VBUS – if 5V power is necessary, Arduino Pro Mini/Shield combination can be powered with 5V on RAW pin, the VCC trace cut off VBUS and RAW and VBUS connected.
As soon as first prototype is tested, I will post CAD files and also make boards available at BatchPCB. Stay tuned!
Blue Arduino USB Host Shield tied to telephoto lens mount
Developer Si Li shared his version of PTPDevinfo.pde, which fits into older Aduinos. Si wanted to get PTP device information from Canon EOS 500D, but he only has 16K Seeduino at hand. So he stripped devinfoparser off all unnecessary strings leaving only ones essential for parsing Canon EOS camera device info.
The modified devinfoparser files are available from “Downloads” section.