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Documentation for JP17 and JP18 on the CubeSat Kit Development Board

PostPosted: Fri Aug 11, 2006 4:28 am
by aek
The CubeSat Kit Test Board B Rev B (PCB P/N 705-00254 Rev B) and the CubeSat Kit Development

Board Rev C (PCB P/N 705-00194 Rev C) have a configurable RS-232 interface to allow for many

different means of connecting the CubeSat Kit to a PC or other terminal via RS-232.

In all cases, a DB-9 male-to-male Null-modem cable between the CubeSat Kit Development Board

and PC/terminal is required.

The naming compatibility between the two PCBs is as follows:


00194 U7 JP12 JP13 JP17 JP18
00254 U7 JP12 JP13 JP907 JP908

We will use the nomenclature of the Rev

C Development Boards in this discussion.

Therefore the description below is applicable to all Rev B Development Boards (because each

one now has a Tets Board B Rev B as well) and all Rev C Development Boards. The Rev A

Development Board can also use the Test Board B Rev B.

The default jumper settings for all of these boards is for there two be two jumpers fitted

on JP12 so that USART0 is connected to the RS-232 interface. This way, you can e.g. send

debug messages from the MSP430 to a terminal, or accept commands from a terminal. The sample

test code in salvo/prod/prod1/sysx accepts commands (e.g. sleep, temperature) from a

terminal and echos results to a terminal via USART0 with the jumpers in their default


The orientation of the jumpers is as follows:


00194 Rev A 2 horizontal (i.e. left-to-right of PCB) jumpers
00194 Rev B 2 horizontal jumpers
00194 Rev C 2 vertical (i.e. top-to-bottom of PCB) jumpers
00254 Rev B 2 vertical jumpers

The orientation of the jumpers was changed on Rev C of the Development Board so that all of

the jumpers are now arranged vertically (JP12 was an exception on Revs A and B).

Now, to the meat of your question:

The additional Jumpers JP17 and JP18 allow for more advanced uses of the RS-232 interface.

(JP13 is for power control -- either leave it empty or connect a jumper between pins 5 and 6

to force the MAX3221 on all the time). In order to use JP17 or JP18, JP12 should be

disconnected i.e. the jumpers should be removed from JP12.

JP17 controls which signal is sent out of the MSP430 to the PC/terminal, and JP18 controls

which signal from the PC/terminal is routed to the MSP430:

JP17 pin descriptions
1-2: RX1 (echo)
3-4: TX1 (out)
5-6: RX0 (echo)
7-8: TX0 (out)

JP18 pin descriptions
1-2: RX1 (in)
3-4: RX0 (in)

To mimic JP12, connect JP17 pins 7&8 and JP18 pins 3&4.

To route USART1 to the RS-232 interface (instead of USART0), connect JP17 pins 3&4 and JP18

pins 1&2.

To snoop on what is coming into the MSP430 on USART1 via either the MHX or the USB, connect

JP17 pins 1&2 and leave JP18 open/empty.

All 2-row connectors are numbered in the same way -- pin 1 can be identified by a square pin

(look on the underside of the PCB), pin 2 is directly across, etc. Pin 1 is in the upper

left corner for vertically-arranged connectors (H1 & H2) and in the lower left for

horizontally-arranged connectors (JP12, JP17, JP18).

The arrangement and pinout of each multi-row connector is reflected in the schematics.

Only a single signal should ever be routed to the MSP430's receive pin (e.g. P3.5 (RX0) or

P3.7 (RX1). Having two signals (e.g. one from the MHX and another from the RS-232) will

cause conflicts.

As of Rev B and later, current-limiting resistors are in place to avoid any potential

overcurrent conditions (e.g. connecting a TX output from the MSP430 to the TX output of the


I have been working with both UART0 and UART1 on the MSP430F169 which was provided
with the CubeSat Kit Development board, and I have reach a point where I need to be able to

view output transmitted by UART1. I had hoped that this would prove as simple as switching

the MAX2331 connection over from UART0 to UART1 and been done with it. Unfortunately, after

reviewing all of the CubeSat documentation I have at hand I cannot find anything with a

detailed explanation of JP17 and JP18 which seem designed specifically for the task of

switching the source of the MAX3221 connection.

Please inform me of where I can find a description of exactly what these two jumpers effect

and how they can be used to modify the setup of the MAX3221.