SGL Observatory Automation. ASCOM Motor Focuser Control Getting Started Guide

Transcription

1 SGL Observatry Autmatin ASCOM Mtr Fcuser Cntrl Getting Started Guide Written by Christian Guenther (yesyes) Dcument versin V September 2011

2 Intrductin SGL Observatry Autmatin is an pen surce prject t cntrl the creatin f sftware, hardware and interfaces t autmate an astrnmical bservatry using the Arduin pen standard, with ASCOM supprt fr apprpriate devices. This guide deals with the Fcuser Cntrl part f the prject. This allws yu t cntrl yur DIY mtr fcuser via the ASCOM standard r via a stand-alne Windws applicatin. What yu need - Hardware - Sftware A biplar stepper mtr with 1.8 degree steps / 200 steps per revlutin r better (less degrees / mre steps are better) One f the supprted stepper mtr driver circuits One Arduin micr cntrller bard 3rd party sftware The Arduin Prgramming Sftware The ASCOM Platfrm 5.5 r higher SGL Observatry Autmatin Sftware (dwnlad frm Files sectin f the SGL Observatry Autmatin Yah! Grup) The sftware that will run n the Arduin bard. This is called a sketch and cmes in the frm f.pde files. These files are text files cntaining the surce cde f the sketch. This needs t be cmpiled and upladed t the Arduin via USB using the Arduin sftware. Files -> SGL Sftware -> Fcuser -> Current Versin SGL_Fcuser_Driver_nlcd_2_0_0F_zip.pde The libraries are required t cmpile the Arduin sketch Files -> SGL Sftware -> Fcuser -> Current Versin Libraries.zip The SGL Fcuser ASCOM driver. This is the sftware that needs t be installed n the PC that yu want t use t cntrl the fcuser. This allws yu t cntrl the fcuser thrugh 3 rd party astrnmy sftware that supprts ASCOM fcuser cntrl. Files -> SGL Sftware -> Fcuser -> Current Versin SGLAscmFcuser V2_00_00B Setup.exe (ptinal) The Fcuser Cntrl Stand-alne applicatin. This is a separate Windws applicatin that allws yu t directly cntrl yur fcuser withut ASCOM supprt. Files -> SGL Sftware -> Fcuser -> Current Versin SGL_Fcus_StandalneV1_00_03.zip

3 - Skills Mechanical skills t munt the stepper mtr nt yur telescpe fcuser mdel. This can be dne in many different ways and depends n yur specific fcuser mdel. Sme sldering will be required. Sme f the circuits f this prject are quite small and sensitive; specifically the Arduin and the EasyDriver. If yur sldering skills are a bit rusty r lacking, then I recmmend practicing n smething less sensitive first. The Hardware Overview This is an verview f hw everything needs t be cnnected The cnnectin between the PC and the Arduin is a simple USB cable. The Arduin will be pwered frm the USB bus. The stepper driver cnnects t the Arduin via a few signal lines and a Grund line (GND). The wires cming ut f the stepper mtr then cnnect t the driver bard. The pwer supply fr the stepper mtr als cnnects t the driver bard. The Arduin can be any reasnably mdern mdel. The Arduin Duemilanve (Italian fr 2009), Un and Mega are ppular. I persnally have chsen an Arduin Nan because it s quite small but has the same functinality as the If yu have nt dealt with an Arduin befre, I recmmend having a lk at the Arduin website and get an idea what it is all abut. As fr the driver, 3 types are supprted: the EasyDriver bard, the L293 driver chip and the LadyAda AFmtr bard. I persnally have nly used the EasyDriver, s I will cncentrate n this driver frm nw n. The prcedure will be different fr ther drivers. The stepper mtr shuld be a biplar stepper mtr with 1.8 degrees per step (less is better). That s the equivalent f 200 steps per rtatin (mre is better). The stepper can have 4 r 6 wires but nly 4 will be used. These steppers can be salvaged frm ld printers fr example. Yu can als find sme cheap nes n Ebay. Yu can ask n the Yah! Grup if yu are nt sure whether a particular stepper will be suitable. The pwer supply depends n the stepper. The EasyDriver can handle up t 30Vlts. G a little higher than what the stepper is rated fr. That will make sure that the stepper has enugh trque t turn the fcuser. I m using a 12V pwer supply fr my 5V rated stepper.

4 Cnnecting everything up On the Arduin side yu need t cnnect 3 wires; ne n a GND pin and 2 n digital I/O pins. The default I/O pins are pin 2 fr directin and pin 3 fr step signals. Yu can chse different pins and specify the pins yu used in the Arduin sketch later. These 3 wires g t the EasyDriver s DIR, STEP and GND pin. Then cnnect the stepper pwer supply t the EasyDriver. The 4 wires f the stepper mtr als cnnect t the EasyDriver. Mre n that later. This is what it shuld lk like: This particular diagram shws an Arduin Nan. The pin names are the same n all Arduins.

5 Cnnecting the stepper First a wrd f warning: Yu must never discnnect the stepper mtr while the EasyDriver is pwered. Ding this will destry the driver chip. Make sure the wires dn t cme lse while yu are testing. If yu have a datasheet fr yur stepper, then find ut which pair f wires is ne cil and which pair is the ther cil. Cnnect ne pair t A n the EasyDriver and the ther pair t B. It des nt matter which pair is which. If yu cnnect them the ther way arund, the stepper will just rtate in the ther directin. This can be crrected in the Arduin sketch. Als, each pair des nt have plarity. It des nt matter which way yu cnnect each pair. If yu have a 6 wire stepper, then dn t use the middle wire f each cil. If yu d nt have a datasheet, yu can easily find ut the pairs using a cntinuity tester r better an Ohm meter (required when yu have a 6 wire stepper). Fr a 4 wire stepper just take the wires and measure cntinuity r resistance. If yu find 2 wires with a lw resistance r cntinuity, that s ne cil. The ther 2 wires are the ther cil. The 6 wire stepper is a little mre tricky. Yu will need t measure the resistance. Cntinuity is nt enugh. Yu need t find pairs with higher resistance than ther cmbinatin f wires. In the diagram belw there will be higher resistance between A and A than between A and A COM (because the cil is lnger). With this type f stepper yu will nt use A COM and B COM. Once yu knw which wires are pairs, cnnect ne pair t the A terminals n the EasyDriver and the ther pair t the B terminals.

6 Munting the Stepper n the Fcuser There are several ways t cnnect the stepper shaft with the fcuser shaft. Yu can use a direct cupling; ideally a flexible ne. Or yu can use gears r belt and pulleys. This is up t yu and hw yu can attach the stepper t the fcuser. If yu use gears r belt yu can chse a gear rati; the higher gear n the fcuser. A higher gear rati allws fr finer adjustment but it takes much lnger fr the fcuser t travel lnger distances. I find a 2:1 rati with a 0.9 degree stepper fine enugh. There is really nt much I can suggest hw yu munt the mtr t the fcuser. Yu will need t find sme way f attaching a metal bracket t the fcuser that hlds the stepper in the right place. Make sure yu knw what every screw n yur fcuser is fr befre yu lsen any f them trying t find an attachment pint. This hw I slved the prblem:

7 A slutin using a universal cupling:- And ne with a direct cupling nt the shaft (cmmercial item):- The Sftware Installing the Arduin Sftware Yu can skip this step if yu already have the Arduin Sftware installed frm a different prject. The Arduin Sftware is an IDE (Integrated Develpment Envirnment) that runs n Windws, Mac OS X and Linux. This is where yu wuld develp sftware that runs n an Arduin and it is als used t uplad the sketch nt the Arduin. Fr this prject the Arduin Sftware will nly be used t make small surce cde mdificatins and then uplad the sketch t the Arduin bard. It is nt required when using the fcuser. Therefre yu dn t need t install it n the same PC that yu will use t cntrl the fcuser. It is, f curse, n prblem t install it all n the same machine. First yu need t dwnlad the Arduin Sftware frm here: Then install and cnfigure the Arduin Sftware. This is explained n the Arduin website here: Feel free t fllw the examples prvided n the Arduin Website. The blink example sketch is a gd and ppular way t check if everything is set up and wrking crrectly. Cpying the Libraries The libraries required t cmpile the Arduin sketch. They cntain extra bits f surce cde that the SGL Fcuser sketch refers t. All yu need t d is t dwnlad the libraries frm the Yah! Grup Files sectin and cpy them t where yu installed the Arduin Sftware. On the website f the SGL Observatry Autmatin Yah! Grup g t Files -> SGL Fcus cntrl Easy Driver -> Driver Versin 2_00_00 There dwnlad Libraries.zip Then pen the zip file and cpy all its cntent t the libraries flder f the Arduin Sftware. Let s say yu installed the Arduin Sftware under D:\arduin-0021\ then cpy the cntent f Libraries.zip t D:\arduin-0021\libraries. Make sure yu keep the subflders exactly as they are in the zip file.

8 Make sure that the Arduin Sftware is nt running while yu cpy the libraries. If it was running, then clse it and start it again fr it t recgnise the new libraries. Cpying the Sketch On the website f the SGL Observatry Autmatin Yah! Grup g t Files -> SGL Sftware -> Fcuser -> Current Versin Frm there dwnlad SGL_Fcuser_Driver_nlcd_2_0_0F_zip.pde Then pen the lcatin where yu installed the Arduin Sftware and g t the subflder Sketchbk. If this flder des nt exist, create it. Under Sketchbk create a new flder with the same name as the.pde file but withut the.pde extensin. In this case the flder name will have t be SGL_Fcuser_Driver_nlcd_2_0_0F_zip. Then cpy the file SGL_Fcuser_Driver_nlcd_2_0_0F_zip.pde int that flder. Mdifying and Uplading the Sketch Depending n hw exactly yu cnnected everything up yu may need t make sme small mdificatins t the surce cde f the sketch. Yu may need t change the I/O pin numbers in the sketch if yu used nn-default pins. Yu may als need t change the directin f the stepper depending n hw yu cnnected the stepper cils t the EasyDriver. Yu need t check and maybe mdify the I/O pin numbers nw. The stepper directin and a few ther things may need t be mdified later. Open the sketch in the Arduin Sftware.

9 Lcate the fllwing 2 lines int dirpin = 2; // Easy Driver Directin Output Pin int stepperpin = 3; // EasyDriver Stepper Step Output Pin Edit the pin numbers t reflect yur wiring. Fr example if yu cnnected the DIR input f the EasyDriver t Arduin digital pin 12 and the STEP input t pin 9, edit these 2 lines the fllwing way: int dirpin = 12; // Easy Driver Directin Output Pin int stepperpin = 9; // EasyDriver Stepper Step Output Pin If yu used an analgue I/O pin, prefix the pin number with an A. Fr example if yu cnnected the DIR input f the EasyDriver t Arduin analgue pin 4 and the STEP input t analgue pin 5, this is what the 2 lines shuld lk like: int dirpin = A4; // Easy Driver Directin Output Pin int stepperpin = A5; // EasyDriver Stepper Step Output Pin N need t mdify anything else at this mment. Click n the Save buttn in rder t save the mdificatins yu made. Nw make sure the Arduin bard is cnnected t the PC via USB cable and the crrect COM prt and Arduin bard type selected as explained n the Arduin website. Then

10 click the Uplad buttn. This will cmpile the sketch int binary frmat and uplad it t the Arduin bard. When the uplad has finished the Arduin will start running the sketch immediately. If yu get any errrs at this stage, check n the Arduin website fr a slutin and/r ask fr help n the Yah! Grup. Installing the Stand-alne Applicatin The Stand-alne applicatin ffers a way f cntrlling the fcuser directly withut ther sftware. This can be used t test yur build. Yu can als use this applicatin t cntrl yur fcuser while bserving / imaging if yu d nt want t use ther ASCOM cmpatible sftware. On the website f the SGL Observatry Autmatin Yah! Grup g t Files -> SGL Fcus cntrl Easy Driver There dwnlad SGL_Fcus_StandalneV1_00_03.zip Then extract the files in the zip archive and run setup.exe in rder t install the Stand-alne applicatin. Testing yur stepper using the Stand-alne Applicatin Nw it s time t test what yu have built and dne s far. Cnnect everything up as described and plug in the Arduin t the PC using the USB cable. Then start the Stand-alne applicatin yu just installed. Make sure the Arduin Sftware is clsed at this pint because it will keep the COM prt t the Arduin pen therwise. A COM prt can nly be pened in ne applicatin at a time.

11 Nw select the COM prt that is assigned t yur Arduin bard and click Cnnect. Then enter a value in the field abve Set Steps. 100 is a gd starting pint. Then click Set Steps and then n Set Relative. Nw when yu click n In r Out the stepper shuld make the number f steps in that directin. 100 steps is prbably a very small mvement. T make bigger steps, enter a higher number and click Set Steps again. If the stepper is mving and des s in the right directin, then yu re dne. The nly thing left t d is t install the SGL Fcuser ASCOM Driver if yu want t use that. If the stepper des mve but in the wrng directin, i.e. the fcuser mves ut when yu click the In buttn, then yu can crrect fr this in the Arduin sketch. Clse the Stand-alne applicatin (fr it t clse the COM prt) and lad the sketch int the Arduin Sftware again. (see Mdifying and Uplading the Sketch). In the sketch find the fllwing line blean Directin = true;//true is ne way false is ther.change t false if mtr is mving in the wrng directin Change it t blean Directin = false;//true is ne way false is ther.change t false if mtr is mving in the wrng directin Then uplad the sketch t the Arduin bard again.. (see Mdifying and Uplading the Sketch).

12 Nw clse the Arduin Sftware again and start the Stand-alne applicatin and test again. The stepper shuld nw mve in the ppsite, crrect directin. If yu experience any ther issues at this pint (fr example the stepper is nt mving at all) please ask fr help n the Yah! Grup. Installing the ASCOM Platfrm ASCOM stands fr Astrnmy Cmmn Object Mdel and represents a standard way f cntrlling varius types f astrnmy equipment frm a Windws PC. It cnsists f the equipment independent ASCOM Platfrm sftware and ASCOM drivers fr each device yu want t cntrl. If yu are already cntrlling ther equipment, such as yur telescpe munt, frm yur PC, then it is quite likely that yu already have the ASCOM Platfrm installed. Check if it is versin 5.5 r higher. If yes, then yu re fine and yu can skip t the next step. If it is lder than versin 5.5, then yu need t upgrade. If yu dn t have the ASCOM Platfrm installed r yu need t upgrade, dwnlad the ASCOM Platfrm sftware frm here: Installatin is straight frward. Just run the dwnladed file and fllw the n-screen instructins. Installing the SGL Fcuser ASCOM Driver The SGL Fcuser ASCOM Driver is the sftware that tells the ASCOM Platfrm hw t cntrl this particular fcuser. This allws any sftware that supprts ASCOM fcusers t cntrl the mtr fcuser yu are building withut knwing the specifics f this fcuser. On the website f the SGL Observatry Autmatin Yah! Grup g t Files -> SGL Fcus cntrl Easy Driver -> Driver Versin 2_00_00 Frm there dwnlad SGLAscmFcuser V2_00_00B Setup.exe Then run this file in rder t install the driver. This will just install the ASCOM driver fr yur fcuser. Yu will nt see a new applicatin installed. Once the driver has been installed yu can pen the applicatin that supprts the ASCOM fcuser. This applicatin shuld have an ptin smewhere where yu can select which fcuser t cntrl. The driver yu just installed shuld appear in the list f available fcusers as SGLAscmFcusCntrl Cnnecting yur applicatin with the SGL fcuser causes a windw t pen that lks very similar t the Stand-alne applicatin. Yu can nw cntrl yur fcuser frm yur astrnmy sftware and als frm this windw.

13 That s it. Yu re dne. Again, if yu have any prblems r questins befre r while building yur mtrised fcuser, please ask n the Yah! Grup that yu can find here: Gd luck with yur build and clear skies fr actually using it.