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Haystack Saturn I Board

Saturn I is a board for prototyping low power wireless solutions using OpenTag/DASH7. It can be used for other purposes as well, but it has a set of features optimized for low-power wireless systems.

Open Source Design Files

Saturn I is licensed via the GPLv3. The schematics and board design files are done in DipTrace, and they are available on GitHub (see link below). OpenTag firmware supports the Saturn I, which is also available on GitHub. Parties interested in a non-GPL version of the Saturn-I design should contact JP Norair to discuss licensing terms.

Building Saturn I Boards

If you decide to build your own Saturn-I boards and resell them, contact JP Norair in order to get a link to your storefront posted on this page.

Otherwise, you can get Saturn-I boards fully produced, on-demand, by Tempo Automation. Tempo has the design on file and is ready to go, just tell them how many you need. If you want to stuff your own boards and save money (at the expense of time and frustration), there's a ZIP package in the repository ready to go to OSHPark, as well as the necessary assembly files, drawings, and stencil gerbers. Saturn-I is not designed to be assembled by hobbyists, so be forewarned, as it uses some very small surface mount components.

Metric vs. Imperial

Saturn-I is designed in metric, so use the metric gerbers unless your assembly shop is imperial-only. All RF equations are in metric (SI), so we make the board in metric. Plus, imperial is a stupid system.

Basic Attributes

Type Notes
MCU STM32L151CC 16MHz Cortex M3, 32KB SRAM, 256KB Flash, 8KB EEPROM
RF SPIRIT1 Configurable for 169, 315, 433, 868, or 915 MHz
RF Antenna SMA connector
Main I/O Bus USB 1.1 Via STM32L1 USB interface
Other I/O Arduino Uno R3 headers Signals not 100% congruent to Uno R3 spec, see Saturn I schematic
Main Power 3.4-5V USB input Brought-down to 3.3V via LDO
Secondary Power 3V CR2450 Used for backup power, via automatic load switch
Status LEDs 1x Green, 1x Orange Generally used for RF TX/RX
Opt. WiFi ESP-06 module interface Saturn I contains footprint for ESP-06 module & integrated antenna

Feature Descriptions

Low Power Wireless Networking

Saturn-I is designed to be attached via USB or powered by a CR2450 Lithium Coin cell. Using the coin cell – and OpenTag – the battery runtime is about 2 days for “always on,” about 3 years in a low duty configuration, or about 7 months in a configuration that micro-sleeps and effectively appears “always on.”

Power Supplies & Battery Switching

When attached to USB power, or any 3.4-5V supply (Vin), the battery will be switched off and all power will come from the 5V supply. The ESP-06 WiFi subsystem and any attached shields are only supplied with regulated 3.3V power when the Saturn is attached to a suitable Vin supply. However, attached shields may draw unregulated power from the CR2450, via the Vbatt pin on J1. Usage of the Vbatt pin is not recommended, because the CR2450 has extremely limited current supply capability.

Battery Charging Shields

There is no battery charging capability in Saturn I, although you could a lithium-ion rechargeable battery pack shield to provide battery charging features. Shields of this type will also supply power to the ESP-06 subsystem, because the Saturn treats it as Vin, so make sure to spec a large enough Li-Ion battery to provide the necessary current. As a rule of thumb, don't use less than 1000mAh for such a design.

Other Information

“Saturn-I” is the first board in the Saturn series. All Saturn boards will feature STM32 MCUs and have the same Arduino-like form factor. It is named “Saturn” after the Roman deity, because STMicro engineering is mainly in Grenoble, France and various parts of Italy (at least Milan and Catania). All of these places were important areas of the Roman Empire.

opentag/board/haystack-saturn-i.txt · Last modified: 2015/10/10 16:28 by jpnorair