The original idea for the Redux Model 1 Mobile Internet Device (MID) was announced less than a month ago. The first week was spent working on the overall form factor. The second week brought a first design candidate based on the OpenMoko platform. The third week lead to a second design architected around the OLPC XO. For the fourth week of work, we have a third revision ready, and this one looks very much like a winner. Not only did we identify most components for the main logic board, but we also found a suitable reference industrial design to house them. Best of all, we might even have a way to improve upon the iPhone’s already amazing design, by bringing the first Multi-Touch/Dual-Force device to market. Not bad, not bad at all…

Everything started when we received an email from Phil Coyne, CEO of SiMa Systems, introducing us to the concept of the user Interface Plane (uIP), which is best described as a reference design for handheld devices incorporating SiMa Systems’ patented Multi-Touch/Dual Force (MT/DF) activation touch sensor, providing for an enhanced user experience and flexibility for designers and manufacturers. Translation: these guys figured out a way to put all the components we need into a neat enclosure, with the coolest touch sensor technology you could dream of.

Two weeks ago, I suggested the use of a back touch sensor with the Redux Reverso design. What SiMa is offering is both back and front sensors, with multi-touch capabilities, dual force touch activation (think point and click), high resolution, and continuous calibration. On top of that, the company developed a reference design for an enclosure that would perfectly match our sizing requirements, while reducing part count, optimizing thinness, improving heat dissipation, and increasing durability by utilizing the functional components as case parts. Also, according to the design, the user needs only turn a single set screw to release the back panel for assembly and disassembly for field upgrades or other service requirements.

This design is so promising that we decided to break all engineering rules for the development of consumer electronics devices. Instead of starting from the core components and making our way out, we started from the outside enclosure and made our way in, by selecting components that could fit into it. Here is where such an extreme development process took us so far:

Display

SiMa Systems’ MT/DF technology can accommodate virtually any LCD display, therefore we decided to select one that would offer very high resolution. We are still evaluating several candidates, but one that looks really promising is Toshiba’s LTD089EXWS, which offers a W-XGA (1280 x 768) resolution with an 8.9" diagonal, bringing pixel density to about 167dpi. The transflective color LCD panel will use LED for backlighting, improving brightness and reducing power consumption, while making the device mercury/lead free. Including LED backlight, power consumption is 2.94W.

Logic Board

After reviewing very many options (including the promising Bug Labs platform), we managed to convince ourselves that the only way we could get a device to market in less than a year while matching our crazy ambitious form factor requirements was to develop our own logic board using existing modules and System on a Chip (SoC) components. Essentially, the logic board will be a backplane hosting the power control unit and providing standard connectors for off-the-shelf modules: a computer module, a Wi-Fi and Bluetooth module, a broadband cellular connectivity module, a GPS module, an audio module, a camera module, an accelerator module, and a MT/DF module.

Power Control Unit

The power control unit is at an early specification stage, but should support the use of multiple Li-ion batteries, one embedded into the MID, and up to three provided by the magnetic keyboard. The selection of a power control system is currently underway.

Computer Module

While Intel’s recently announced Moorestown looks very promising, it won’t be available until 2009, therefore should be considered for future designs only. Silverthorne is an interesting option for our first device, but we would need to get Intel’s help to use it at such an early stage of its development. OLPC’s use of an AMD core is also interesting, but power consumption remains too high, and the level of integration it offers is not dense enough to accommodate our form factor requirements. As a result, we might have to go for an ARM core, using Samsung’s amazing S3C6400, which is also powering Apple’s iPhone in some proprietary variant. In order to reduce development time and cost, we could go for a Computer on Module package provided by Embedian, the upcoming COM-7310. It is based on the ARM1176 core, runs at 533MHz, provides a 266MHz bus, embeds an SM502 graphics co-processor from Silicon Motion, supports the encoding and decoding of MPEG-4/H.263/H.264 at up to 30fps, and draws 300mA at 5V (1.5W). Most important of all, it can run the Linux operating system, even though support for SD is not available yet, while support for CF is.

Wi-Fi and Bluetooth Module

For the Wi-Fi and Bluetooth module, we are currently considering the W2CBW003 from Wi2Wi. This System-in-Package is a complete multifunction 802.11 and Bluetooth 2.0 radio. It supports 802.11b/g, 802.11e (QoS), 802.11i (Security), and Bluetooth 2.0 with EDR, while providing a fully integrated coexistence solution for using both 802.11 and Bluetooth at the same time. Drivers for Linux are available, and power consumption for dual mode transmission is 275mA at 3.3V (907mW).

Cellular Connectivity Module

For cellular connectivity we have selected the Expedite product line from Novatel. These modules are especially attractive because they all natively support the Linux operating system, and are available for both the North American (EU860D) and the European (EU870D) markets, supporting HSPDA, UMTS, WCDMA, GPRS, and EDGE networks. A module for EV-DO networks is available as well (E725). These modules are packaged using the PCI Express Mini Card form factor, and will be user swappable. The SIM slot will be located next to the SD slot, in a configuration that makes it easy for users to take SIM and SD cards in and out on a daily basis. Drivers for Linux are available. Power consumption should be less than 150mW in navigation mode (1fix/s).

GPS Module

For the GPS module, we will go for one based on the SiRFstarIII chip. Many options are available, but one we particularly like is the JP13-S-LP from Falcom USA. Drivers for Linux are available. Power consumption is unknown at present time.

Audio Module

Thanks to the AC-97 audio codec interface and PCM serial audio interface embedded into the Samsung S3C6400, the audio module only requires a stereo amplifier and can be integrated directly into the backplane. The LM4857 from National Semiconductor and used for the Neo 1973 could be a good candidate. Power consumption with stereo headphones is 75mW. The loudspeaker and microphone have yet to be selected.

Camera Module

Thanks to the 8-bit ITU 601/656 camera interface embedded into the Samsung S3C6400, the camera module does not need any active components and can be integrated directly into the backplane. It can support up to 4M pixel for scaled and 16M pixel for un-scaled resolution. The camera itself has yet to be selected.

Accelerometer Module

In order to support dynamic screen orientation, we need to embed one or two 3D accelerometers onto the backplane. For these, we could use the LIS302DL from STMicroelectronics.

MT/DF Module

The Multi-Touch/Dual-Force is under development and very few details are available about it at this point. A custom set of drivers for Linux will be developed specifically for the Redux Model 1. Power consumption is unknown at present time.

At present time, and based on publicly available information, this design should allow us to remain under the $500 price point for a limited production batch of 2,500 units. Also, based on our current design, power consumption will be the most critical element of the project from an engineering standpoint. Every milliwatt will count!