Viper is the first generation HONEY Breakout Board. Viper breaks out most of the important signal and power lines from the HONEY stack Data Bus & Power Bus, as well as the CAN Bus, to enable connecting to the HONEY flight stack remotely, over cable.
This enables two important capabilities, such as:
- The Flight Stack can be broken into two compartments, and connected seamlessly via cable, continuing to act as one complete flight stack (unless there are relevant data bus signals that aren't broken out).
- The Flight Stack can be broken out to an external payload, which, with the correct receiving connector, can have access to all of the stack data/power/signal lines. This enables using the HONEY flight stack for non-HONEY payloads -- such as ProtoBee's or similar projects.
These functions, as well as a breakdown of the Viper Breakout Pinout, are explained below:
Pinout
Viper comes with three connectors -- two "Payload Breakouts" and one "Master Breakout". They are discussed in detail below.
Payload Breakout
Viper has two Payload Breakout connectors -- this allows for the possibility of daisy chaining vertically or horizontally through the same flight stack. That is, you can "extend" the flight stack downward by having another flight stack below it, connected to the original flight stacks Viper boad, AND simultaneously extend the flight stack vertically, by adding a flight stack above the original flight stack, and connecting it to the other payload breakout.
The Payload Breakout format (meaning, the particular connector, cabling) as well as the specific pinout, is called Venom Breakout.
There is no need for more than two payload breakouts, with the expectation that all boards that receive the payload breakout also have a secondary connector to allow for continued daisy chaining. This is the case, for example, on ProtoBee.
The particular payload breakout itself is a 1.27mm pitch 2x25 pin keyed, shrouded connector. This decision was made to make the breakout as small as possible, and keep the cabling thin. The exact connector, and associated cabling, are:
Connector: Samtec SHF-125-01-L-D-RA Cabling: Samtec FFSD-25-D-XX.XX-01-N
In the above, XX.XX denotes the length -- which can be custom as desired, in inches (2 inch minimum).
The specific pin out for Venom Breakout is the following, with the first row as the top, second row as the bottom, left to right as seen looking into the receptacle from the board-edge.
| 5V | 3.3V BUS | VBATT (4.2V) | 12V | 1.8V | SDA | SCL | MOSI | MISO | SCLK | VA_PWM | CHIRP | R_MCU | R_ALL | S_READY | LOW_PWR | FMODE | SYS_F3 | SYS_F4 | SYS_F5 | SYS_F6 | (+5 S) | (-5 S) | CAN_SPD | GND |
| 5V | 3.3V BUS | VBATT (4.2V) | 12V | VADJ OUT | TX4 | RX4 | TX6 | RX6 | DAC0 | DAC1 | AV29 | AV42 | AV17 | AV16 | AV35 | AV36 | AV37 | AV38 | CAN1_H | CAN1_L | (+12 S) | (-12 S) | 3.3V CAN | GND |
Master Breakout
In addition to the Venom Breakout, Viper also includes a larger, 56-pin 2.54mm (standard) pitch connector known as the Master Breakout -- or, more formally, the Fang Breakout.
The Fang Breakout breaks out the remainder of what the Viper Breakout was unable to breakout, or what was deemed inessential for a payload to have access to. This includes the secondary CAN Bus and some additional avionics GPIO pins.
The Fang Breakout, at time of writing (Aug 10, 2017) has no impending implementation scheme. It exists in the first revision of the HAB Breakout to facilitate two things -- one, the possible eventual need to break out the additional remaining pins, and, more importantly, two -- to enable directly using female jumper wires to tap signals directly from Viper, by providing a standard-pitch connector that can be both directly tapped or cabled.
The Fang Breakout pinout is very similar to the Venom Breakout, with some slight alterations:
| 5V | 3.3V BUS | VBATT (4.2V) | 12V | 1.8V | SDA | SCL | MOSI | MISO | SCLK | VA_PWM | CHIRP | R_MCU | R_ALL | S_READY | LOW_PWR | FMODE | SYS_F3 | SYS_F4 | SYS_F5 | SYS_F6 | CAN2_H | CAN2_L | (+5 S) | (-5 S) | (+12 S) | (-12 S) | GND |
| 5V | 3.3V BUS | VBATT (4.2V) | 12V | VADJ OUT | TX4 | RX4 | TX6 | RX6 | DAC0 | DAC1 | AV29 | AV42 | AV17 | AV16 | AV35 | AV36 | AV37 | AV38 | AVA10 | AV51 | AV52 | AV53 | CAN1_H | CAN1_L | CAN_SPD | 3.3V CAN | GND |