The BBC Computer Substitutes in Izaña are described

Barnes, Ian

Jackson, Barry

Miller, Brek A.

University of Birmingham Research Archive, E-papers Repository

BiSONBirminghamSolar-OsillationsNetworkTECHNICAL REPORT NO. 218BeebSub #56A and BeebSub #56B|BBC Computer SubstitutesIan Barnes, Barry Jakson, and Brek A. MillerThe University of Birmingham, Edgbaston, Birmingham B15 2TT2003 November 20This tehnial report series is published by:SLHigh-Resolution Optial-Spetrosopy GroupShool of Physis and AstronomyThe University of BirminghamEdgbaston, Birmingham B15 2TT, United KingdomTelephone: +44-121-414-4551 FAX: +44-121-414-1438BeebSub #56A andBeebSub #56B|BBC Computer SubstitutesIan Barnes, Barry Jakson, and Brek A. MillerThe University of Birmingham, Edgbaston, Birmingham B15 2TT2003 November 20AbstratThe BBC Computer Substitutes in Iza~na are desribed.1 IntrodutionIn 2003 Deember, the old BBC omputer that was olleting Mark I data from the BBC salerswas replaed with a new PC. The BBC salers [1℄ have a 10-ms window in whih the data anbe read. Although the typial interrupt lateny for the Iza~na PC is 25s, the worst-ase latenymeasured while the system is under a heavy load is 30ms. This means that if the omputertries to read the data from the salers itself, it may miss points.To solve this problem, we have reated a BBC Computer Substitute (BeebSub) whih readsthe data from the salers in plae of the BBC omputer. It then forwards the data to the newPC over an RS-232 onnetion.Two of these devies were built and sent to Iza~na in 2003 Deember. They are alledBeebSub #56A and BeebSub #56B. The rst devie atually started out as PIC DevelopmentSystem #3 (Pidev #3) [2℄. It was used to test the interrupt lateny of the PC and was thentransformed into BeebSub #56A.2 DesignThe BeebSub is a 1U rak ase ontaining two main boards: the Supply Board and the PICBoard.1Figure 1: The front panel.3 Front PanelThe front panel is shown in Figure 1. It ontains a main power swith, three LEDs to verifythat the power supply is working, and four LEDs to show the state of the RS-232 lines.4 ConnetionsThe rear-panel is shown in Figure 2. The rear-panel onnetors are shown in Table 1. Thepin-out of the RS-232 onnetor is shown in Table 2.Figure 2: The rear panel.Table 1: Rear-Panel ConnetorsConnetor Label DesriptionCN1 25-pin female D BeebSub RS-232 Serial dataCN2 9-pin female D Saler DataCN8 blak 4-mm Analog groundCN9 male IEC MainsTable 2: RS-232 Connetor (CN1)Pin Label Desription1 CGND Chassis ground2 TxD Transmit data to BeebSub3 RxD Reeive data from BeebSub7 GND Signal ground2Table 3: Saler Data Connetor (CN2)Pin SignalHeaderPinPICPinPICNameDesription1 MT 1 33 RB0/INT Not empty2 CB1 2 34 RB1 Next digit is ready3 CB2 3 35 RB2 Request next digit4 D0 5 37 RB4 Data5 D1 6 38 RB5 Data6 D2 7 39 RB6/PGC Data7 D3 8 40 RB7/PGD Data8 DGND 10 Digital Ground9 CGND 12 Chassis GroundTable 4: Saler-Data CableStation: Izana.Cable: 12-wire, 7/0.2-mm, Shielded.Length: 6mCable Label: Saler Data Saler DataConnets to: BeebSubBBC SalersConnets to Label: Saler Data noneConnetor:9-pinmaleD14-pinmaleIEEE-488MT 1 6 blakCB1 2 12 brownCB2 3 13 redD0 4 2 orangeD1 5 3 yellowD2 6 4 greenD3 7 5 blueDigital Gnd 88><>:1711violetgreywhiteChassis Gnd 9 | shield35 Supply BoardD104D103D102D101FILTER2200uF 35VC1082200uF 35VC1071uFC106L7815Q1031uFC105+15V1uFC104L7915Q1021uFC103-15V+15V1R1031uFC102L7805Q1011uFC101+5V1R1021MR1011234J91234J10256+5V-15V+15VTO PICBOARDJ202D105 D106D107 D108F1011AF1021A1234J103561234J1045612J81234J105561234J10656SPARE SPARE1234J10751k2R1041k2R105270R106TOPOWERBOARDLEDSPARESPAREFigure 3: Ciruit drawing for the Supply Board.The Supply Board supplies regulated 15V and +5V to the BeebSub. The iruit shematiis shown in Figure 3. This is a single-sided board. The omponent layout and bottom-side traksare shown in Figure 4 on the next page.4Figure 4: Supply Board omponent layout and bottom-side traks.56 PIC Board1234J21156789101234J21256789101234J2135678910+5V1234J221567891011121234J222567891011121234J22356789101112+5V1234J251561234J252561234J25356+5V1234J242567891011121234J243567891011121234J24156789101112+5VXT201+5V1uFC2011234J232567891011121234J233567891011121234J23156789101112+5VTXRXRA0/AN0RA1/AN1RA2/AN2/VREF-RA3/AN3/VREF+RA4/T0CLIRA5/AN4/SSRB0/INTRB1RB2RB3/PGMRB4RB5RB6/PGCRB7/PGDRD0/PSP0RD1/PSP1RD2/PSP2RD3/PSP3RD4/PSP4RD5/PSP5RD6/PSP6RD7/PSP7RE0/RD/AN5RE1/WR/AN6RE2/CS/AN7234567333435363738394089101920212227282930OSC1/CLKINOSC2/CLKOUT1314VDDVDDVSSVSS11321231MCLR/VPP1RC0/T1OSO/T1CKIRC1/T1OSI/T1CKIRC2/CCP1RC3/SCK/SCLRC4/SDI/SDARC5/SDORC6/TX/CKRC7/RX/DT1516171823242526PIC 16F877U201Figure 5: Ciruit drawing for the PIC Board.The PIC Board ontains a PIC 16F877 in a 40-pin ZIF soket. Header onnetors areprovided for all signals to be onneted to the PICs input and output pins. A MAX232 RS-232onverter is also provided.The main iruit shemati for this board is shown in Figure 5. The iruit shemati forthe RS-232 setion is shown in Figure 6 on the next page.61uFC2061uFC2071uFC2081uFC2041uFC205+5V1345C1+C1-C2+C2-6V-2V+Vcc1611 T1in T1out 1412 R1out R1in 1315GND+5V5k400k+5V-TO-+10VVOLTAGE DOUBLER+10V-TO--10VVOLTAGE INVERTERMAX232U202+10V13121110987654321252423222120191817161514CN11234J1Q20310uFC203Q201270R20110uFC202Q202 Q2041 2 3 4 5 6J201820R202270R203820R204D1 D3-10VGREEN GREENRED REDD2 D41 2 3 4 5 6CN201LED BOARDRXTX+5V-10VPIC BOARD100kR205100kR206Figure 6: Ciruit drawing of the RS-232 setion of the PIC Board.7Figure 7: PIC Board omponent layout and bottom-side traks.8Figure 8: PIC Board omponent layout and top-side traks.97 RS-232 LED BoardThe RS-232 LED Board ontains four front-panel-mounted LEDs and displays the state of theRS-232 lines. The bottom side traks and the omponent layout are shown in Figure 9.Figure 9: RS-232 LED Board omponent layout and bottom-side traks.8 Power LED BoardThe Power LED Board ontains three front-panel-mounted LEDs and displays the state of thepower-supply lines. The bottom side traks and the omponent layout are shown in Figure 10.Figure 10: Power LED Board omponent layout and bottom-side traks.9 RS-232 InterfaeThe BeebSub ommuniates with the omputer through an RS-232 onnetion. The onnetorfor this link is at the far left on the rear panel. It is a 25-pin, female d-onnetor. The only pinsused in this onnetor are: 1 (hassis ground), 2 (transmit data, TxD), 3 (reeive data, RxD),and 7 (signal ground). The BeebSub is ongured as data ommuniations equipment (DCE)and transmits on pin 3 and reeives on pin 2. The RS-232 settings are 9600 baud, 8 bits, noparity. No handshaking (hardware nor software) is provided.Four LEDs on the front panel show the state of the TxD and RxD lines. The left olumnis for the TxD line and the right olumn is for the RxD line. The red LEDs on the bottomare illuminated when the orresponding line is low. The green LEDs on the top are illuminatedwhen the line is high.10The BeebSub ommuniates with the omputer using one-line messages. Eah messagebegins with a dollar sign (\$", ASCII 36) and ends with a arriage-return/line-feed pair. TheBeebSub will send an asterisk (\*", ASCII 42) followed by a two-harater heksum at the endof eah message.The heksum is alulated by XORing the ASCII values of all of the haraters in themessage that follow the dollar and preede the asterisk. The dollar and asterisk are not inludedin the heksum alulation. The resulting heksum is inluded in the message as a two-haraters hexadeimal value.The following messages are sent from the BeebSub to the omputer.9.1 Counter Data$C,<DIGIT-STRING >,<OVERFLOW >*<CK ><CR ><LF ><DIGIT-STRING > The string of hex digits read from the BBC salers.<OVERFLOW > Zero (\0", ASCII 48) if all of the digits read from the BBC salers are presentin this message, or one (\1", ASCII 49) if the BBC salers returned moredigits than would t in this message. The BeebSub an buer only 96 digits.The BeebSub will send one ounter-data message every time the BBC salers raise the MT line.9.2 Error Message$E,<ERROR-CODE >,<DESCRIPTION >*<CK ><CR ><LF ><ERROR-CODE > A numeri error ode.<DESCRIPTION > A desription of the error in text form for humans to read.The BeebSub an send these two error messages:$E,01,!MT stuk low*72$E,02,!MT stuk high*0B10 Parts ListA list of some of the omponents purhased in order to build the BeebSub are shown in Table 5.The pin-outs of some of the omponents is shown in Figure 11.11Table 5: Parts ListManufaturer'sPart NumberDesriptionUnitCostC107,108 Rapid 11-0765 2,200-F 35-V 85ÆC eletrolyti ap 0.275CN80Rapid 22-2500 2-pin 0.156-in. female header 0.013D101-108 Rapid 47-3144 1N5401 100-V retier diode 0.024F101,102 Rapid 26-4614 0.9-A resettable fuse 0.26J8 Rapid 22-2590 2-pin 0.156-in. header 0.036Q101 Rapid 47-3290 L7805CV 1-A voltage regulator 0.145Q102 Rapid 47-3300 L7915CV 1-A voltage regulator 0.155Q103 Rapid 47-3294 L7815CV 1-A voltage regulator 0.145Q201,203 Rapid 47-0156 ZVN2106A MOSFET 0.22Q202,204 Rapid 47-0174 ZVP2106A MOSFET 0.29U201 Rapid 73-3202 PIC16F877-04P dip40 3.90U202 Rapid 82-0148 MAX232CPE RS-232 line driver dip16 1.18XT201 Rapid 90-0625 4-MHz erami resonator 0.19RS 224-234 rak ase 1U 84HP 254mm 52.57RS 364-7185 IEC inlet lter 14.44Rapid 75-0330 DPST red visiroker swith 0.53Rapid 22-1580 40-pin ZIF soket 8.27Rapid 33-3525 M3-12 hex spaer pk25 1.62Rapid 33-4210 M3-6 s/s pan-head pk100 1.80Rapid 33-4260 M3-6 s/s sk pk100 1.70Rapid 88-2622 50-VA 18-V 1.39-A toroidal transf 6.38Rapid 36-0250 twisted-vain 9:9ÆCW 1TO-220 heatsink 0.3812................................OUTPUTCOMMONINPUTFRONT VIEWTO-220(a) L7815................................OUTPUTCOMMONINPUTFRONT VIEWTO-220(b) L7805................................OUTPUTINPUTCOMMONFRONT VIEWTO-220() L7915.................DRAINGATESOURCEPIN VIEWE-LINE(d) ZVN2106A.................DRAINGATESOURCEPIN VIEWE-LINE(e) ZVP2106A1234567891011121314151617181920 2122232425262728293031323334353637383940MCLR/VppRA0/AN0RA1/AN1RA2/AN2/Vref RA3/AN3/Vref+RA4/T0CKIRA4/AN4/SSRE0/RD/AN5RE1/WR/AN6RE2/CS/AN7VddVssOSC1/CLKINOSC2/CLKOUTRC0/T1OSO/T1CKIRC1/T1OSI/CPP2RC2/CPP1RC3/SCK/SCLRD0/PSP0RD1/PSP1 RD2/PSP2RD3/PSP3RC4/SDI/SDARC5/SDORC6/TX/CKRC7/RX/DTRD4/PSP4RD5/PSP5RD6/PSP6RD7/PSP7VssVddRB0/INTRB1RB2RB3/PGMRB4RB5RB6/PGCRB7/PGDTOP VIEW(f) PIC 16F87712345678 910111213141516C1+V+C1 C2+C2 V T2outR2in R2outT2inT1inR1outR1inT1outGNDVTOP VIEW(g) MAX232Figure 11: Pin-outs of various omponents.13Referenes[1℄ Clive P. MLeod. Mark I saler system. BISON Tehnial Report Series, Number 184,High-Resolution Optial-Spetrosopy Group, Birmingham, United Kingdom, July 2002.[2℄ Ian Barnes, Barry Jakson, and Brek A. Miller. Pidev #3|A PIC developmentsystem. BISON Tehnial Report Series, Number 217, High-Resolution Optial-SpetrosopyGroup, Birmingham, United Kingdom, November 2003.14

BeebSub #56A and BeebSub #56B BBC Computer Substitutes

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