Turtle Sense communications board v.0.25a - Revision history

Sam: /* Smart Sensor connections */ Other connections

2014-08-29T01:47:07Z

Smart Sensor connections: Other connections

Sam: /* Known issues */ connections

2014-08-12T09:14:50Z

Known issues: connections

Sam: dab

2014-08-11T21:39:11Z

dab

Sam: reorganize

2014-08-11T21:26:42Z

reorganize

Sam: Sam moved page Turtle Sense Communications board v.0.25a to Turtle Sense communications board v.0.25a

2014-08-11T21:20:11Z

Sam moved page Turtle Sense Communications board v.0.25a to Turtle Sense communications board v.0.25a

Sam: Sam moved page Circuit Description for Turtle Sense v.0.25a to Turtle Sense Communications board v.0.25a

2014-08-11T21:19:44Z

Sam moved page Circuit Description for Turtle Sense v.0.25a to Turtle Sense Communications board v.0.25a

Sam: more

2014-07-16T06:39:09Z

Sam: /* Power supply */ http://us.sanyo.com/eneloop/About-eneloop-Batteries

2014-07-03T20:42:48Z

Power supply: http://us.sanyo.com/eneloop/About-eneloop-Batteries

Dave: Modify Cable Table

2014-07-03T19:37:15Z

Modify Cable Table

Dave: Add table of cable connections

2014-07-03T02:46:18Z

Add table of cable connections

@@ Line 98: / Line 98: @@
 |}
 Several pins on the microprocessor are used to communicate with the [[Circuit Description for Smart Sensor v.0.24|Smart Sensor]]: SnsrRst, TX/RX ON, SensorTX, SensorRX, Interrupt, and Tamper.  SnsrRst controls an analog switch (U9) which switches the 3.3V power going out to the sensor along with Ground.  The output of U9 is normally connected to the 3.3V switch input.  A logic high pulse on SnsrRst connects the sensor power to ground to reset the sensor.   Interrupt is a signal which the sensor sends to the Comm board when it wants to communicate -- to send or receive data.  Tamper is a signal which the sensor constantly keeps high.  If the sensor cable is unplugged the Comm board can detect that by the logic low on the Interupt signal.
 ==Transceiver==

← Older revision		Revision as of 09:14, 12 August 2014
Line 115:		Line 115:

	* Connections are hard wired to the board for the LEDs, switches and cables that are used. In future versions, these connections will use headers or some arrangement of sockets and plugs so that the board can be easily serviced and replaced.		* Connections are hard wired to the board for the LEDs, switches and cables that are used. In future versions, these connections will use headers or some arrangement of sockets and plugs so that the board can be easily serviced and replaced.
		+
		+	* The connection between the communications board and the smart sensor uses shielded Cat 5 cable, so there are 9 connections to each board, and a pair of 9 pin molex connectors that allow the two units to be connected. This is the most labor intensive part of the project. The cable required reinforcing so that it would not break from repeated bending from connection and disconnecting. These were quickly found to be prone to failure if extreme care was not used. This is not a reasonable expectation of workers in the field. To deal with this problem we cast poly urethane around the base of the connectors and the ends of the cable, reinforcing the weakest part of the connection. This worked very well, but the result takes too much skilled labor to make it conducive to production in large numbers. We are considering alternate methods of making the connection between the sensor and communications units for future versions. We would like to make the connections wireless, but it is not possible to transmit from under 2 feet of wet salty sand. We are considering running power over a coax cable, having an antenna at the end of a cable from the sensor, or combining the options so both are possible. Coax has a long history of being used outdoors, and connectors can be replaced in minutes if they corrode or fail. Power over coax has been used for decades for TV mast antennas. We're considering using Sub-1G or Bluetooth Smart for the RF transmission.

@@ Line 1: / Line 1: @@
 [[File:PhaseTwoCommBoard.jpg|Thumb|right|400px|The Comm board is on top, the telephony board plugs in underneath.]]
-The '''Turtle Sense communications board v.0.25a''' is the controlling circuitry for Turtle Sense.  It connects, via Cat5 cable, to a [[Circuit Description for Smart Sensor v.0.24|Smart Sensor]]. A piggybacked M2M plug-in telephony board made by Janus enables GPS and cellular communications.
+The '''Turtle Sense communications board v.0.25a''' is the controlling circuitry for Turtle Sense.  It connects, via Cat5 cable, to a [[Turtle Sense Smart Sensor board v.0.24|Smart Sensor]]. A piggybacked M2M plug-in telephony board made by Janus enables GPS and cellular communications.
 * [[Turtle Sense Communications PCB Schematic v.0.25a|PCB Schematic]]
 ==Power supply==

@@ Line 1: / Line 1: @@
 [[File:PhaseTwoCommBoard.jpg|Thumb|right|400px|The Comm board is on top, the telephony board plugs in underneath.]]
-Turtle Sense v.0.25a is the Communications (Comm) Board which connects to the remote [[Circuit Description for Smart Sensor v.0.24|Smart Sensor Board]] and to a piggybacked M2M plug-in telepony board made by Janus.
+The '''Turtle Sense communications board v.0.25a''' is the controlling circuitry for Turtle Sense.  It connects, via Cat5 cable, to a [[Circuit Description for Smart Sensor v.0.24|Smart Sensor]]. A piggybacked M2M plug-in telephony board made by Janus enables GPS and cellular communications.
+* [[Turtle Sense Communications PCB Schematic v.0.25a|PCB Schematic]]
 ==Power supply==
 The Comm Board is powered from a battery pack of 8 [http://us.sanyo.com/eneloop/About-eneloop-Batteries low self discharge rechargeable NiMH AA batteries].  The battery pack is about 11V fully charged and has a capacity of 2 amp-hours.  The positive battery input to the board first passes through a diode (D1) which protects the circuitry from damage if a battery pack is somehow connected backwards.  The battery voltage is filtered by two capacitors, C7 and C1.  The battery level is monitored by a resistor divider R11 and R12.  The voltage on R12 (BattMon) is measured by an analog to digital converter, or ADC, in the microprocessor.  The battery pack powers two power supplies on the board:

@@ Line 106: / Line 106: @@
 ==GPS and antennae==
-The telephony board has a built in GPS unit.  There are connections on the board for two antennae, one for GSP reception and the other for Cell reception.
+The telephony board has a built in GPS unit.  There are connections on the board for two antennae, one for GSP reception and the other for Cell reception.  The GPS unit is currently only used in the hand-held unit (see below), though it will likely be used in future firmware updates to track the device if it is disturbed.
 ==Known issues==
-* The battery monitoring circuitry, originally designed with a much higher resistance voltage divider was found to be too high an impedance for the ADC converters in the microprocessor.  Because of this, lower resistors had to be substituted in the board, causing a constant current drain of approximately 60 uA, or about 1.5 mAh a day.  While not a tremendous power loss, it is more than the power used by both microprocessors and the motion sensor.  Future versions of the board will have a switch to turn the voltage divider circuitry on and off, so the voltage will only be monitored periodically.
+* The battery monitoring circuitry, originally designed with a much higher resistance voltage divider was found to be too high an impedance for the ADC converters in the microprocessor.  Because of this, lower resistors had to be substituted in the board, causing a constant current drain of approximately 60 uA, or about 1.5 mAh a day.  While not a tremendous power loss, it is more than the power used by both microprocessors and the motion sensor combined.  Future versions of the board will have a switch to turn the voltage divider circuitry on and off, so there won't be any current drain when the voltage is not being monitored.  The only significant drain on the batteries is from the plug-in telemetry board, so the voltage will only be monitored each time there is a telephony connection.

← Older revision	Revision as of 21:20, 11 August 2014
(No difference)

← Older revision	Revision as of 21:19, 11 August 2014
(No difference)

@@ Line 3: / Line 3: @@
 ==Power supply==
-The Comm Board is powered from a battery pack of 8 rechargeable NiMH AA batteries.  The battery pack is about 11V fully charged and has a capacity of 2 amp-hours.  The positive battery input to the board first passes through a diode (D1) which protects the circuitry from damage if a battery pack is somehow connected backwards.  The battery voltage is filtered by two capacitors, C7 and C1.  The battery level is monitored by a resistor divider R11 and R12.  The voltage on R12 (BattMon) is measured by an analog to digital converter, or ADC, in the microprocessor.  The battery pack powers two power supplies on the board:
+The Comm Board is powered from a battery pack of 8 [http://us.sanyo.com/eneloop/About-eneloop-Batteries low self discharge rechargeable NiMH AA batteries].  The battery pack is about 11V fully charged and has a capacity of 2 amp-hours.  The positive battery input to the board first passes through a diode (D1) which protects the circuitry from damage if a battery pack is somehow connected backwards.  The battery voltage is filtered by two capacitors, C7 and C1.  The battery level is monitored by a resistor divider R11 and R12.  The voltage on R12 (BattMon) is measured by an analog to digital converter, or ADC, in the microprocessor.  The battery pack powers two power supplies on the board:
 * a 3.3V linear low power voltage regulator (U3) which powers the microprocessor (U1) and related circuitry on the board
 * a 5.0V switching voltage regulator (U4) which powers the Phone Board.

@@ Line 32: / Line 32: @@
 {| class="wikitable"
 | Comm Board
-| Wire Color
+| Signal
 | Molex 9-pin
 | Wire Color
 | Smart Sensor
 |-
-| Pin No.
+| J1 Pin No.
+|
 | Pin No.
+|
-| (Soldered)
+| J1 Pin No.
 |-
 | 7
-| Brn
+| Comm TX+
 | 8
 | Brn
@@ Line 56: / Line 50: @@
 |-
 | 6
-| Brn-Wh
+| Comm TX-
 | 7
 | Brn-Wh
@@ Line 62: / Line 56: @@
 |-
 | 9
-| Or
+| Comm RX+
 | 9
 | Or
@@ Line 68: / Line 62: @@
 |-
 | 8
-| Or-Wh
+| Comm RX-
 | 6
 | Or-Wh
@@ Line 74: / Line 68: @@
 |-
 | 5
-| Grn
+| TX/RX ON
 | 5
 | Grn
@@ Line 80: / Line 74: @@
 |-
 | 4
-| Grn-Wh
+| SensorPwr
 | 4
 | Grn-Wh
@@ Line 86: / Line 80: @@
 |-
 | 3
-| Blu
+| Interupt
 | 3
 | Blu
@@ Line 92: / Line 86: @@
 |-
 | 2
-| Blu-Wh
+| Tamper
 | 2
 | Blu-Wh
@@ Line 98: / Line 92: @@
 |-
 | 1
-| Shield
+| Ground
 | 1
 | Shield

@@ Line 29: / Line 29: @@
 ==Smart Sensor connections==
 The sensor is connected to the Comm board via about 20 ft of underground Cat5e shielded cable.    A short stub of the cable connects to the Comm board and to a 9-pin male Molex connector.  The main length of cable connects to the sensor board and to a mating female Molex connector.
 Several pins on the microprocessor are used to communicate with the [[Circuit Description for Smart Sensor v.0.24|Smart Sensor]]: SnsrRst, TX/RX ON, SensorTX, SensorRX, Interrupt, and Tamper.  SnsrRst controls an analog switch (U9) which switches the 3.3V power going out to the sensor along with Ground.  The output of U9 is normally connected to the 3.3V switch input.  A logic high pulse on SnsrRst connects the sensor power to ground to reset the sensor.   Interrupt is a signal which the sensor sends to the Comm board when it wants to communicate -- to send or receive data.  Tamper is a signal which the sensor constantly keeps high.  If the sensor cable is unplugged the Comm board can detect that by the logic low on the Interupt signal.