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Questions about customizing the Acousonde™

Added 4 February 2009

This FAQ is for "power users" who are contemplating significant modifications to the Acousonde.

Underneath its special-purpose focus, the Acousonde is a flexible miniature data-acquisition system. With core ARM9 clock speeds up to 208 MHz and, at the same time, extensive power-saving measures both within and outside the microprocessor, the Acousonde electronics can handle large data throughput despite their small size and low power consumption. Several colleagues have shown interest in applying the Acousonde beyond its original scope.

Regrettably, our volumes are so low that we cannot provide the documentation and interaction necessary to support customers wishing to customize the Acousonde. Even customers skilled with acoustic systems and embedded-systems programming must still have basic information about the Acousonde's architecture to customize it. Unfortunately we simply do not have the resources to prepare and provide that information.

We hope that this situation will change. Having put all this work into the Acousonde we would love to see it find its full potential. Large orders or large collaborative efforts, in particular, would provide the support needed to document the Acousonde for those wishing to adapt it to their own applications. As a step towards this goal, some of the questions received about customizing the Acousonde are answered below.

To summarize: we can not support customization of the Acousonde's digital electronics at the present time except in the context of a large order or additional support.

We apologize in advance if we can not respond in depth to other questions regarding user customization.

Electronic requirements and limits

How powerful is the microprocessor?
It is an ARM9 with an ARM vector floating point (VFP) coprocessor. The maximum core clock speed is 208 MHz, while the maximum bus speed is 104 MHz.
How much memory can be installed?
The Acousonde comes with 16 gigabytes of onboard data storage by default, with capacities up to 128 gigabytes available. It is also possible for the microprocessor to act as a USB host instead of a USB device, and write data out to a USB flash or disk drive. If this approach is used, storage is limited by the size of the external USB drive. Note that the Acousonde cannot provide the 5 V power required by USB peripherals.
What are the power requirements? Can I supply my own power?
The Acousonde requires 3 to 5 volts (5.5 V absolute maximum) which is buck-converted down to 2.8 V and several lower voltages. There is a minimally-tested circuit that can provide boost power from as little as 2 volts. Power requirements are still being characterized (Feburary 2009) but worst-case current draws in the most demanding situations should be less than 100 mA.

When attached to a USB cable, the Acousonde derives power from the cable.

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Control/interface questions

Is there any way to control the Acousonde remotely?
Not at present. The Acousonde's user interface has been developed entirely around infrared commanding via a Palm PDA. The Acousonde does have a serial port used as a debugging console, but this port is not available to the outside world.

To control the Acousonde via its serial port would require customized cabling to its serial console and custom programming to support a serial command-line interface.

Are any spare ports or A/D inputs available?
Yes. There is a spare 2.8 V UART in addition to the 2.8 V console UART; there are two spare general-purpose 2.8 V I/O lines; and there are three channels of the microprocessor's built-in 10-bit A/D available. All of these require significant custom programming to support but the hardware is there.
How about a pulse-width modulation output?
Yes, a PWM is available too, although it is tied to the base of an open-drain power FET; the drain is expressed to a through-hole on the board, not the PWM itself. This feature is intended for grounding a resistive load.
I want to provide power and communications myself. How about a connector?
It is possible to mold an underwater connector in with the Acousonde instead of its battery housing. As long as you provide power and USB to the Acousonde via this connector, the Acousonde will function normally. Other pins of the connector can be used to support remote serial communication or provide external analog or digital signals.
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Customizing signal inputs

Can I cable my own external hydrophone to the Acousonde?
Yes; however, this is not as simple as it sounds. The Acousonde is designed as a sealed instrument for maximum reliability and simplicity as well as to control cost, and departing from that concept while maintaining reliability will require additional design, tooling, and testing. Customers who must have functionality beyond the original Acousonde concept are encouraged to contact us to discuss a non-recurring engineering (NRE) effort.
If we do an NRE to support my external hydrophone, Can I use my own preamplifier?
Probably not, even in the context of a non-recurring engineering (NRE) effort. The Acousonde can provide only +2.8V single-sided power to its preamplifiers. Most vendors' preamplifiers use higher voltage rails, so you will probably need to use the Acousonde's preamplifier board. This can be placed inside the Acousonde if your cable run will be very short, or we can supply it to you to integrate with your hydrophone for longer cable runs.
What if I give you my own hydrophone? Will you mold it into the Acousonde for me?
Yes, provided it is small enough. Your hydrophone would take the place of the high-frequency hydrophone, and must fit in a space no larger than 0.625" (absolute maximum, smaller dimension) by 0.780" (absolute maximum, larger dimension). We would install it in combination with our own preamplifier. This is option B003-UH. Note that this option does not include any calibration for your hydrophone beyond what you give us.
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Customizing the operating software

Can I modify the Acousonde's internal operating software for my own purposes?
No, not at present. We are considering providing for a user-replaceable software module but these plans are still in a very early stage.
Can I collaborate with you in modifying the internal operating software?
Cooperative development would allow users experienced in programming to have direct access to the Acousonde Operating System (AcOS) source code. In the context of a large order or collaborative project this could work well. Several intellectual-property questions would need to be resolved.
What development environment do you use to maintain the operating software?
The Acousonde Operating System is written in ARM assembly language and C, and compiled using a standard GNU Makefile in concert with the GNU C toolchain. Most development takes place within the Eclipse Integrated Development Environment (IDE). Versioning is provided by a Subversion repository.
Can I run my own operating system on the Acousonde? Like embedded Linux?
The Acousonde is based on an ARM9 with plenty of flash and SDRAM memory. There is also a miniature JTAG port. So the Acousonde electronics should be fully compatible with embedded Linux.
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