2023-03-26 - VN-300 Rugged Harness

Owned by Anonymous, created
Last updated: 2023-03-31 by Jack Greenwood
2 min read

Change Description

ICARUS

VN-300 Rugged Harness

Jack Greenwood

Description of Change

Documenting the harness & wiring for the VN-300 for ease of use in future.

Implementation

Brief

Upon discussion in RFC thread, it has been decided to power the VN-300 through the Pixhawk. Please see VN-300 Harness for more information.

Configuring the VN-300 to work in UART allows compatibility with the GPS2 Port on the Pixhawk. The VN-300 takes a 5V input from the Pixhawk and uses TTL (UART) for transmitting and receiving from GPS2 Port.

SCL, SDA, SYNC_OUT, SYNC_IN lines are unused because UART does not require synchronization.

GPS_PPS - line unused because GPS2 Port has no PPS pin.

Math

Not including antennas, the VN-300 has a maximum power draw of 1.25 [W]. The antennas use an external power supply coming from a PDB. Each antenna has a maximum current draw of 12 [mA], which gives the power consumption of the antennas to be 2 * (12 * 12) = 0.288 [W]. Factoring this in, we have a maximum power draw of the VN-300 to be 1.25 + 0.288 = 1.538[W]. Given that we are looking for an upper bound on the current and the switching regulator on the PDB is not perfect, we assume that the regulator is 95% efficient. This results in the value of our max power needing to be multiplied by 1.05 to compensate for non-perfect conversion. Using P = IV, we have I = (1.538 * 1.05) / (5) = 323 [mA] (rounded up). Thus, the maximum current draw is 323 [mA] at 5 [V].

Connection Diagram

 

 

 

Important Links

VN-300 Brief datasheet: https://www.vectornav.com/docs/default-source/datasheets/vn-300-datasheet-rev2.pdf?sfvrsn=1e27aef3_10

VN-300 Full Datasheet is not public, but can be found in our Discord in #ee-bookshelf.

Antenna datasheet: https://www.tallysman.com/app/uploads/2018/11/Tallysman®-TW2412-Datasheet.pdf

Reason for Change

Defining connection of VN-300 to Pixhawk.

Priority

High

Impact of Not Responding to Change

Mounting of the VN-300 on the drone not being properly defined increases ambiguity which leads to confusion.

What Groups, People, Sub-teams Need to be Notified?

  • Anthony

  • Daniel

  • EFS

  • Nathan

  • EE

Change Impact

Additional Parts/Resources Required and Costs

Parts for the connector.

Fitting the VN-300 on the drone.

Impact on deadlines

Should take 3 days to complete. 1 day to assemble the connector, and 2 days to test that the connector works.

Alternatives and Recommendations

N/A

Comments

N/A

Make sure to create a thread in the ‘rfc’ chat in discord (here). Share a link to your rfc in your post so it can be approved!

Change Request Sign Off <System Integration>

Status

Accepted / On Hold / Rejected / More info Requested

Comments

Signatures/Name