Support Engineering Group : Elevator Release Controller
This page last changed on Aug 03, 2011 by tm.

Project: Elevator Release Controller


Support Engineers:  Thom Maughan, Craig Okuda

Electronics and Firmware: Thom Maughan

Mechanical and System: Craig Okuda 

**See attachment for Fusion USBL software release procedure.  
 

Problem Statement: 

  • Elevator (Platform) is weighted and sunk up to 4000m. Deployment duration is 30 to 45 days at which time the weight is released and the positive buoyant elevator then rises to the surface.
  • The problem: an ROV descends and pulls the release cord - this is expensive (~$10k).    
  • The solution is to leverage the existing transponder to create an acoustic release actuator.    This consists of:
    • SonarDyne UM - 7970 Super Sub-Mini acoustic transponder with RS232 interface - (1200 baud, 8 data bits, no parity, 1 start/stop bit).
    • MBARI Elevator Release Controller (ERC) connected to SonarDyne Super Sub-Mini
      • There are several extraneous characters which come out of the port when the unit transponds so the ERC needs to filter these out.
      • Three character command sequences with trailing carriage return:
        • REL (output after receiving 3 release commands within 50 seconds. Release is command 0 on the sonardyne ANT tester)
        • EBL (transponder replies are enabled. Enable is command 1 on the sonardyne ANT tester)
        • DBL (transponder replies are disabled. Disable is command 2 on the sonardyne ANT tester)
        • EIR (enable instrument replies, which enables two-pulse depth replies. EIR is command 3 on the ANT tester)
        • DMS (disable instrument replies. DMS is command 4 on the ANT tester).
    • The ERC decodes the 'REL' control message and triggers a relay that provides 9-12v to a motor which moves a cam that then pulls the release cord and drops the weight.    Relay and switch logic with the index switch should turn the motor off.
    • The cam has a Gianini index switch in parallel with the ERC motor control relay that detects the home position of the motor and de-activates power to the motor.   
    • A Manual Release switch is required for test.
      • Manual release test will be activated when power is supplied to the microprocessor thru the interface connector.
      • A test switch will be provided on the PCB board - not accessible
    • The motor will only activate infrequently - a couple times to test and then after 30 - 45 days it will operate when commanded by the transponder.
    • The micro will just sit and wait for a "REL" string to come from the transponder.  When it gets a release command it will turn on the gear motor. 
    • It will take about 15-30 seconds for the motor to turn 360 degrees until it hits the index/home switch and stop. 
    • The micro must also turn off power to the motor when the manual release/test button is pressed for more than 10 seconds. 
    • It should again turn the motor on until it goes 360 to the index/ home position. 
    • There will be a FET in parallel with the magnetic motor interrupter switch  
    • Turn on FET until magnetic switch goes on then turn off FET


 Requirements

  • Reliable
    • With a working transponder set (top-side and bottom-side), the ERC must drop the weight when commanded.
    • 45 day duration.   ERC controller will be designed for 4x battery power budget (180 days)
      • Option A: CR2032 coin cell - assume 150 mAH at 3.0v.
        • Coin cell holder to prevent backward battery insert (Shrink wrap)
      • Option B: 3.6v AA Lithium Battery (2000mAH)
      • Low power microprocessor and controller circuitry
        • Goal: Listen for RS232 signal with less than 10 uA, reliably receive "REL" command
    • Operation at 0 degrees C with humidity in a sealed container. Able to withstand 85 degrees C (sun baked housing)
    • Able to drive 12 v Pittman Motor with gearing
      • Batteries able to supply momentary 1.5 A (guess) startup current
      • Batteries able to supply continuous 400 mA (guess) continuous current for 10 seconds (guess)
  • Testable
    • switch to test operation, ANT test set for simulating transponder signal.
  • Fault Tolerant
    • Fault mode: Seawater in the connector. Isolate the motor connections, both ground and power, to prevent connector corrosion from activating the motor.
  • Maintainable
    • Marine Operations Team should be able to 'easily' acquire and replace batteries.
    • Goal: select one type of battery for both ERC and Motor
  • Space Constraints
    • Motor batteries (9v - 12v) and ERC board and battery (3v - 3.6v) must fit in a cylindrical pressure housing with internal dimensions approx. 2.5" x 5.5".
    • The ERC board should target a size of 2" x 2".

Processor Selection: 

  • MSP430F1232 chose for it's low power operation and ability for fast wakeup on RS232 input: 
    • Low Supply Voltage Range 1.8 V to 3.6 V
    • Ultralow-Power Consumption:
        • Active Mode: 200 µA at 1 MHz, 2.2 V
        • Standby Mode: 0.7 µA
        • Off Mode (RAM Retention): 0.1 µA
        • Five Power Saving Modes
        • Wake-Up From Standby Mode in less than 6 usec
    • 16-Bit RISC Architecture, 125 ns Instruction Cycle Time
    • Clock Module Configurations:
      • 32-kHz Crystal
    • 16-Bit Timer_A With Three Capture/Compare Registers
    • 10-Bit, 200-ksps A/D Converter With Internal Reference, Sample-and-Hold,
    • Serial Communication Interface (USART0)
    • Serial Onboard Programming, No External Programming Voltage Needed, Programmable Code Protection by Security Fuse
    • Supply Voltage Brownout Protection
    • MSP430F1232: 8KB + 256B Flash Memory, 256B RAM
    • Plastic 28pin TSSOP


RS232 Selection

  • Low Power, able to receive in standby mode
  • MAX3222 selected - 0.1uA in standby and able to receive
    || ~SHDN (RX) || ~EN (TX) || T-OUT || R-OUT || Power ||
    0 0 Z Active 1 uA
    0 1 Z Z 1 uA
    1 0 Active Active 25 mA
    1 1 Active Z 25 mA

FET Selection


Battery Selection

  • 3.0v to 3.6v for Controller
    • Lithium preferred for long shelf life.   Option A is a coin cell replaced each deployment or Option B is a AA that gets replaced every 5 years (assuming shorting plug is removed between deployments).
  • 9v to 12v for Motor
    • 8 x 1.5v Alkaline replaced for each deployment.



Digital Camera AA Comparison

The table below summarizes the important differences and similarities among AAs commonly compatible with digital cameras.

Comparison: AA Batteries for Digital Cameras

Feature Nickel Metal Hydride (NiMH) Nickel-Cadmium (NiCd) Lithium Alkaline Lithium 3.6v
Nominal voltage 1.25 1.25 1.5 1.5 3.6
Rechargeable Yes Yes No No No
Capacity per AA (mAh) 1,300-1,800 1,100  for high-capacity types, 650 standard ~2,700 2,500  
Cost per AA ($US) $2.00-3.75 $1.50-2.00 (high-capacity) $2.25-2.50 $0.25-1.00 $8 - 12
Cost per amp-hour $1.54-2.09 $1.36-1.81 $0.83-0.93 $0.10-0.40  
Cost per Ah for 1,000 uses* $1.54-2.09 $1.36-1.81 $830-930 $100-400*  
Weight, approx. (gm) 25 22 14 23  
Runtime in a digital camera Very good Good Excellent Very poor Excellent
High-drain performance Excellent Excellent---even better than NiMH Excellent Very poor Excellent
Self-discharge rate 10% first 24 hours, then 10%/month; average 1-2%/day 50-67% that of NiMH Negligible Extremely low Negligible
Shelf life (once fully charged) 3-5 weeks at least Slightly better than NiMH 10 years 5 years 10 years
Voltage curve slope during discharge Nearly flat over 1st 90% of capacity Same as NiMH Nearly flat Strongly falling at start Nearly flat
Lifetime charging cycles 500-1000 More than NiMH n/a n/a  
Maximum safe long-term trickle charge rate (mA) 10% of rated capacity (C/10), but C/20 or less is safer 2-3% of rated capacity (C/33) n/a n/a  
Operating temperature range Same as NiCd Good: -4° to 113°F, but capacity suffers at low temps Excellent: -40° to 140°F Poor Excellent: -40° to 140°F
Chemistry NiMH, where alloy M is usually LaNi5 NiCd (cadmium instead of nickel-metal alloy at the anode) LiFeS2 Zn/MnO2  
Heavy metal toxicity None High, due to cadmium content None ?? None
Availability beyond mail order On-line and chain retailers Chain drug and hardware stores Same as NiCd Everywhere On-line, some drug stores carry CRV3


Batteries Selected:

  • Controller - saft 3.6v Lithium.   10 year life
  • Motor - 8 x 1.5v alkaline changed with each deployment.



Tasks:

  • Design (complete)
  • Schematic Layout (complete)
  • PCB Layout (complete Apr. 22) 
  • PCB fab (goal: send out Apr. 24 )
  • Parts purchase (board qty 10) 
    • Digikey (ordered 22 Apr 08)
      • MSP430F1232
      • MAX3222
      • FET
      • Diodes (switching, protection)
      • Inductors
    • Garrett Electronics (ordered 22 Apr 08)
      • Surface mount resistors (10, 100, 10k, 20k, 100k)
      • Surface mount caps (0.1uf, 22uf)
    • RadioShack (ordered 22 Apr 08)
      • Batteries (saft)
      • Battery holders
    • onlinecomponents (ordered 22 Apr 08)
      • Relays (2.30 and in stock vs 8.50 with 10 week backorder from Digikey)
  • Board Bringup
    • Tested MSP430, clock circuit and relay control.   No ECO's related to basic operation.  TODO: test relay logic with motor and mag switch.
    • Errata
      • JTAG connector is improperly layed out (schematic is incorrect).   The even numbered pins are reversed.
  • Firmware (in progress, delayed while working on Valve Pack Controller)
    • supportEng/erc source code repository created (on moonjelly) 
    • cygwin and parallel port emulator from Olimex used for development.
      • Aug 2008.  Had some difficulty getting JTAG working again
    • UART baud rate (1200)
    • rx, tx
    • motor control
    • test button
    • 12v battery monitoring (might need to change the resistors)
    • timer
    • data logging for testing
    • low power mode (wake on RX)
  • Production board build
  • Test
    • soak test to verify power consumption numbers and battery life
    • Test with ANT
  • User / Service Documentation for DMO
  • Drawing Number
    •  10020095 | DSN | Elevator Release Controller | 4/28/2008 |

Ant Setup Procedure for Testing


1200,8,N,1

3=Multi

3=Old Pan

3=Command

2=Set

5=MF

2=ADDR

"2505", "ENTER"

3=COMMAND

"0"=REL, "ENTER"

1=EXIT

5=START (Sends command "0" to 2505)

5=START (Sends command "0" to 2505)

5=START (Sends command "0" to 2505)

(3rd Start sends the release command)

Summary

ON 

3

3

3

4

2

5


Attachments:
elevatorRelease_rev0-3.zip (application/x-zip-compressed)
Elevator Release Procedure.doc (application/octet-stream)
Document generated by Confluence on Feb 03, 2026 16:22