gca125-nl
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— | gca125-nl [2018/11/12 08:56] (current) – created - external edit 127.0.0.1 | ||
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+ | ====== GCA125 Interface for turtoise type turnout drives ====== | ||
+ | [[english|{{ | ||
+ | [[english|Content]] -> [[hardware-en|Hardware]] -> [[hardware-en# | ||
+ | * [[mgv-overview-en|The GCA modules]] | ||
+ | |||
+ | \\ | ||
+ | |||
+ | ^^^^By Peter Giling ^^^^ | ||
+ | |||
+ | ==== Features and facts ==== | ||
+ | {{ : | ||
+ | * 8 individual inputs, commanding 8 individual outputs | ||
+ | * 600 mA max load per output.\\ | ||
+ | * Max 42 Volt per output. | ||
+ | * Time selection for output duration. | ||
+ | * Outputs are activated one by one for power reduction. | ||
+ | * Processor on board is isolated from the board by opto-couplers | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | ===== Description ===== | ||
+ | |||
+ | Controlling a LGB 1201, Kato or Fulgurex turnout-drive, | ||
+ | Even the Bohler WA2 is very nicely useable with this interface.\\ | ||
+ | The normal driver like GCA77 is not suitable for that.\\ | ||
+ | The complexity of this unit is slightly higher.\\ | ||
+ | For GCA drive-units it is standard, to have an isolation between power for the coils or motors and the used network system by means of optocouplers.\\ | ||
+ | That is also done on this board, but in a bit different way.\\ | ||
+ | The processor runs on 5V from GCA50 / CAN-GC2 or GCA_PI02, and the processor drives two optocouplers to send I2C commands to the I2C expanders.\\ | ||
+ | This unit is able to control 8 turnouts, and need 8 inputs from the GCA50 / CAN-GC2 / GCA_PI02.\\ | ||
+ | It is also possible to use a switch for direct activation without GCA50 / CAN-GC2 / GCA_PI02. \\ | ||
+ | You will need a 5 Vdc to activate the processor, connected to pin1(+) and pin 2(-) of J3.\\ | ||
+ | In that case pin3(=input 1) to pin10(=input8) of J3 are to command the motors.\\ | ||
+ | One other option is to use GCA174 DCC or Motorola function decoder, to drive directly from the central unit.\\ | ||
+ | The software in the PIC16F628 is made in such a way that the processor provides a correct timing for the coil, and switch it off after the chosen time.\\ | ||
+ | This will take care that the turnout coil or motor will not be overheated by too long powering.\\ | ||
+ | The time selection is done with the Dipswitch, and counts for all outputs.\\ | ||
+ | The processor in the circuit needs 11 inputs and 18 outputs, and 3 extra for dip-switch reading. \\ | ||
+ | Instead of these 29 I/O ports, smaller PIC processors have only maximum 16 I/O.\\ | ||
+ | |||
+ | \\ | ||
+ | \\ | ||
+ | |||
+ | ===== Old version | ||
+ | |||
+ | [[GCA125-proto-en|This is the original page for this board, created for a home-made prototype.]] | ||
+ | |||
+ | \\ | ||
+ | \\ | ||
+ | |||
+ | |||
+ | |||
+ | ===== The hardware files ===== | ||
+ | | {{: | ||
+ | | {{: | ||
+ | ^ N.B. Self made pc-boards are not supported! | ||
+ | \\ | ||
+ | \\ | ||
+ | |||
+ | ===== Cable to MGV50 / CAN-GC2 / GCA_PI02===== | ||
+ | |||
+ | refer to: | ||
+ | [[PSK-Interface connections-en|**Connection interfaces**]] | ||
+ | \\ | ||
+ | |||
+ | ===== Using GCA125 without GGCA50/ | ||
+ | It is possible to use the GCA125 as a stand alone unit.\\ | ||
+ | A 5V supply should be feeded to J3 (pin1 +, pin2 -).\\ | ||
+ | Pin 3(=1) to 10(-8) should be switched between +5V and - for position select.\\ | ||
+ | |||
+ | ===== Firmware ===== | ||
+ | {{mgv: | ||
+ | \\ | ||
+ | \\ | ||
+ | |||
+ | ===== Led functions ===== | ||
+ | |||
+ | Green led: is on when no output is activated.\\ | ||
+ | It is off when one of the ouputs is active.\\ | ||
+ | \\ | ||
+ | Red led: will flash when one of the ouputs is active.\\ | ||
+ | If flashes as many times as the binary value of SW1.\\ | ||
+ | Led is off when no output is activated.\\ | ||
+ | \\ | ||
+ | |||
+ | |||
+ | ===== Time delay settings ===== | ||
+ | SW1 is used to set the delay time after which the output will be swotched off. | ||
+ | |||
+ | ^ Delay table ^ ^ ^ ^ | ||
+ | | Motor activation | ||
+ | | 0.1 | ||
+ | | 0.2 | ||
+ | | 0.4 | ||
+ | | 0.8 | ||
+ | | 1.6 | ||
+ | | 3.2 | ||
+ | | 6.4 | ||
+ | | 12.8 | ||
+ | |||
+ | ===== Remarks ===== | ||
+ | Inputs, if activated, should remain activated, to keep motor/coil in the chosen position.\\ | ||
+ | GCA50/ | ||
+ | Checking C2 will inverse action.\\ | ||
+ | \\ | ||
+ | ===== Induction knowledge ===== | ||
+ | Motors and single coil dirves, also the ones in turtoise engines, are using coils.\\ | ||
+ | And a coil, feeded with a current, will push back a large power surge, when it is switched off.\\ | ||
+ | That behaviour, for example, is used in cars for creating the ingnition spark.\\ | ||
+ | But in modelrailroad, | ||
+ | In dc systems. it is rather easy to suppress that spark by connecting a diode straight on the coil,\\ | ||
+ | and connected in such a way that the cathode is at the positive side.\\ | ||
+ | Any electronic system will thank you for that. It saves you a lot of trouble.\\ | ||
+ | These diodes are in GCA125 inside the L293D chip, so we do not have worry about that.....\\ | ||
+ | WRONG!! because in most motor driven tortoise units, and also the turnouts, moved by (single-) coils, there is a limit switch\\ | ||
+ | which will disconnect the motor/coil from the driver (in GCA125 the L293D chip).\\ | ||
+ | This switching off then also disconnects the on-chip diodes from the motor/coil! \\ | ||
+ | This problem, by the way, causes many limit switches in turnout coils to fail after some time, due to the generated spark.\\ | ||
+ | Now, one option is to bridge these switches, because with the available timer on the GCA125, the motor will switch of after a chosen timing.\\ | ||
+ | But if we like to keep the switch in function, we need to find another solution.\\ | ||
+ | And specially on motors and single coil units, that is a problem, because there is no +/-. because they will be reversed for reaching the oppossite position.\\ | ||
+ | So a diode cannot be used here\\. | ||
+ | The other solution for that is a VDR or varistor.\\ | ||
+ | These VDR's, (useally here something like a 30V type), will short the motor/coil as soon as the voltage exceeds 30V.\\ | ||
+ | So if you have this situation, use a VDR like VDR-0,25 30, directly connected to coil or motor, and your problem is solved.\\ | ||
+ | |||
+ | | ||
+ | |||
gca125-nl.txt · Last modified: 2018/11/12 08:56 by 127.0.0.1