Product specification and build instructions BV401. I2C Input / Output Board. ByVac 2006 ByVac Page 1 of 10

Transcription

1 Prduct Specificatin and Build Instructins Prduct specificatin and build instructins Jan 006 v0.a ByVac 006 ByVac Page f 0

2 Prduct Specificatin and Build Instructins Cntents. Intrductin.... Features Hw It Wrks Hw It Wrks IC Pwer Output Input Building Testing Using Relay Test Analgue Output Parts List Resistrs... Errr! Bkmark nt defined. 8.. IC Sckets... Errr! Bkmark nt defined LED s... Errr! Bkmark nt defined Dides... Errr! Bkmark nt defined Electrlytic Capacitrs... Errr! Bkmark nt defined. 9. An I/O Prject Descriptin IC Relay Output Mtr Output Analgue Output Analgue Input Feedback System Variables Further Intrductin The is an input / utput bard designed fr the IC interface. It cmplements the ther bards in the prduct range and because it uses IC, des nt take up many I/O lines. The fur pwer utputs can drive dc mtrs frward r reverse, r stepper mtr.. Features Fur high pwer utputs with independent enable fr driving DC mtrs (frward and reverse) r stepper mtr. x screw terminals Tw relay utputs SPDT x 3 way screw terminals One analgue utput Fur analgue inputs Analgue i/ via 8 way plarised cnnectr IC fully addressable analgue range 90h t 97h, chip PCF859 IC fully addressable digital range 70h t 77h, chip PCF8574 High pwer /p chip L93 600mA per channel January 006 f 0

3 Prduct Specificatin and Build Instructins 6 way IC scket fr mating with the BV30 6 way cnnectr fr analgue in / ut way cnnectr and jumper fr external pwer Dimensins 94 x 40mm Weight 50g 3. Hw It Wrks The blck diagram shws that the cnnectin t BV30 is via K, the BV30 can supply pwer +5V and the IC master signals required. The bard can als be used with any ther IC system. There are tw relay utputs with SPDP switches and tw mtr drivers that are terminated with screw terminals. The 4 analgue inputs and ne analgue utput uses a standard 6 way plarised cnnectr. 4. Hw It Wrks 4.. IC IC and its assciated circuitry frms the utput and IC3 is the analgue input. Bth IC and IC3 are IC devices. IC is a serial prtcl allwing varius devices t be cnnected using nly tw wires. All IC devices have an address t distinguish them frm each ther when using the same bus. IC s address is set by jumpers PA0 t PA and IC3 s address is set by AA0 t AA. All devices cme with a fixed base address that can be mdified by these jumpers. IC fr example has a base address f 70h but by default if all f the jumpers are remved this will be 7Eh. ByVac Page 3 f 0

4 Prduct Specificatin and Build Instructins All IC devices have a read and write address, bit 0 is used t indicate which: 0 is write and is read s strictly speaking IC is 7Eh fr write and 7Fh fr read with all f the jumpers discnnected and 70h fr write and 7h fr read when all f the jumpers are in place. The address lines map t the fllwing bits: A A A0 R/ W Using this prject several bards can be used and each have their wn unique address. Further infrmatin can be fund in the data sheet fr the PCF8574 and PCF Pwer Cnnectr K prvides +5V fr the lgic circuits and pwer fr the mtrs via pins 5 and 6 respectively. If this cnnected t the BV30 then this bard (within reasn see later) is capable f supplying this pwer. Fr very heavy lads r lads that may prduce large current spikes, the small pwer supply n BV30 may nt be up t the jb. This f curse all depends n what the BV30 is being pwered with in the first place. T cater fr such circumstances K and JP have been prvided, dides D and D simply prtect the prviding circuits. JP selects whether the mtr supply shuld cme frm K r K Output The PCF8574 is described as an input / utput expander. This is because it is expanding the IC wire bus int 8 I/O lines; a serial t parallel cnverter if yu like. In this circuit it is nly used fr utput. Lines P0 t P5 are taken t IC, P6 and P7 drive the relays. At reset IC is an input device and has a small internal pull up current. This is sufficient t hld Q and Q ff via R and R3. In this way at pwer up the relays are always ff. This is the reasn fr using PNP transistrs. IC is described as a fur channel driver with dides and a lk at the data sheet will reveal that it is capable f delivering 600mA per channel. This is an incredibly simple and lw cst way f driving any inductive r therwise lad. Because f its cnfiguratin tw mtrs can be driven frward r reverse. The device is cnfigured as x channels and each channel pair can be enabled by driving the EN and EN inputs high. Althugh it has been envisaged that tw DC mtrs will be cntrlled, any lad can be applied t the utput f this device. Given the crrect sftware a stepper mtr can als be driven. D3 and D4 are there t prevent any back emf frm being fed int the rest f the circuit, all inductive (nes with cils) lads need this dide prtectin Input The ther half f the circuit is dedicated t analgue input and ne analgue utput. T simplify the circuit the analgue reference is the +5V supply which has been suitably smthed by C and R7. All f the wrk is dne by IC3 and this is cnnected t K3. The base address f IC3, with all the jumpers remved is 9Eh. ByVac Page 4 f 0

5 Prduct Specificatin and Build Instructins 5. Building Using the PCB building is very straight frward. Start with the lwest prfile cmpnents first IC sckets, resistrs and finish with the highest nes; relays, cnnectrs. See appendix A fr tips n cnstructin. Use the verlay t ensure the crrect psitining and rientatin f the cmpnents. Pay particular attentin t the dides, transistrs and electrlytic capacitrs that all must g in the crrect way rund. The red traces in the verlay shw the tp side f the bard, ntice the cpper fill arund the grund pins f IC, this is there t help dissipate heat. Duble check all slder cnnectins, dide and capacitr rientatins. Befre applying pwer see Testing belw. NOTE IC is sldered directly t the PCB (n scket), this is t help it dissipate heat. 6. Testing It is nt pssible t test this bard fully withut having a suitable IC master interface. The BV30 will d nicely and it is assumed yu have built this and tested the nbard IC devices. D nt install the IC s befre switching n. With the IC s remved cnnect up the BV30 t K. This is a straight cnnectr pin t pin, pin t pin etc. When cnnected, with a meter check that there is +5V n the crrect pins fr the IC s. Als if apprpriate check that there is pwer t pin 0 f IC. There shuld be pwer n this if yu have a pwer supply built n the BV30 and JP is in the crrect psitin. If yu are happy that the crrect supply is being fed t the IC sckets, remve the pwer and install the IC s. At switch n (plug K back in) nthing shuld happen, a few quick checks with a meter will suffice fr a preliminary verificatin: PIN Vltage IC 3,8,3,8 +5V Emitter Q & Q +5V Base Q & Q +5V IC pin 4 (SCL), pin 5 +5V (SDA) The vltages at steady state are given abve. The +5V figure may vary frm 4.5V t 5.5V 7. Using The fllwing uses TCB t test the bard: 7.. Relay Test Relay is cnnected t bit 7 s setting this pin lw will cause the relay t energise and yu shuld be able t hear this, Try: CPOKE 6 7 CPOKE 6 55 This will turn relay n and then ff, fr relay tw try: CPOKE 6 9 CPOKE 6 55 Yu can test the ut put t K and K3 using a meter. Fr mre infrmatin n the CPOKE cmmand refer either t the TCB manual r the varius prjects fund n the ByVac web site. 7.. Analgue Output ByVac Page 5 f 0

6 Prduct Specificatin and Build Instructins T carry ut a very simple test cnnect an LDR r ther variable resistance t channel f the A/D cnverter. Fr example between pins and 6 f K3. If yu dn't have any variable resistrs, chse tw different resistrs and slt them in ne after the ther -- and tgether, wrk ut the maths. See the phtgraph fr an example. IC3 has t be set up t read frm channel befre any reading can take place. Als the reading is nt valid until the secnd reading. All f this infrmatin is in the datasheet. D - D4 N Cnnectrs & Sckets PA0-,AA0- Jumper pins 6 JP IC- sckets DIL 6 K way plarised K, K3 6 way plarised K4, K5 way screw terminal K6, K7 3 way screw terminal Miscl Y, Y Relay 5V SPDT PCB -PCB H:\Zed\ASCII-Me\006-dcuments\sub- Appendix A-build instructins.dc (9eH = 58 DECIMAL) CPOKE 58 0 ' This sets channel CPEEK 58 A ' First reading CPEEK 58 A ' Valid reading PRINT A It desn't take much imaginatin t put lines,3 and 4 int a cntinuus lp and bserve the effects f putting yur hand ver the LDR t cut ut the light. It wrked very well fr the ne I was using which has a dark resistance f abut 80k. The abve f curse is just a test, yu will find a full descriptin f what this bard can d in the Hw T sectin.. 8. Parts List Capacitrs Part Value Number C,C3,C4,C6 0.uF 4 C,C5 00uF 6V - electrlytic Resistrs R,R3 k R - R6 0k 6 R8 - R 00k 4 R7 390R Semicnductrs IC PCF8574 IC LN93 IC3 PCF859 Q & Q BC557 ByVac Page 6 f 0

7 ByVac Prduct Specificatin and Build Instructins 9. An I/O Prject utput nly device. This is cnnected t a mtr cntrller and tw relays. The fllwing is repeated frm the Prject that can be fund n the ByVac web site. It illustrates the use f the device in cnjunctin with Tiny Cntrl Basic. Each f the sectins will be dealt with in turn with examples f hw t use them. The set up used fr the experiments given in this text is shwn belw. 9.. Descriptin The is a cmprehensive I/O bard and can be used fr many things. The basis f this prject is t lk at, and give prgram examples f what can be dne. The prject is split int parts that illustrate the different functins f the Bv40 and ends with a temperature feedback system. Nte that there are individual circuit bards available that perfrm the same functin as parts f the. The BV40 relay bard fr example, the relevant circuits are: BV40 - Relay bard * BV403 - Analgue cmparatr - This is nt available n the BV404 - Digital utput - This is nt available n the BV405 - Mtr cntrller bard * BV406 - IC bard * The abve marked * bards are almst exactly the same integrated circuits yu wuld find n the. The cmbines the 3 circuits tgether and makes them accessible by the IC interface. The data sheets fr the parts discusses are: PCF8574 PCF859 L IC 9.3. Relay Output The IC cmmand fr all the digital utputs is CPOKE <device address> <data> because the PCF8574 is a simple singe register device. With all f the jumpers discnnected (pen) the device address is 7eh and this is what will be used fr the examples. The relays are cnnected t bits 6 and 7 f the PCF8574. At switch n the prt assumes a high (input) state. The is designed s that this is the ff state f the relays. It fllws then t switch the relays n the bits need t be taken lw. Relay requires 0 (BFh) Relay requires 0 (7Fh) The is an IC device and will wrk with any IC master device, it des nt have t be anther BV bard. Fr cnvenience all f the examples will assume a BV3xx prcessr bard is cnnected t the. Experiment: Turn n relay, CPOKE &7e &bf yu shuld hear the relay click Turn it ff CPOKE &7e &ff again the relay shuld be heard t click ff Turn n relay, CPOKE &7e &7f Turn ff relay, CPOKE &7e &ff The abve will verify the crrect wrking f the relays. Nte that they wrk ff f the same +5V pwer supply that the IC s use s pwer must be prvided at the IC input cnnectr. This is dne autmatically via the 6 way cnnectr if using the BV Mtr Output This diagram, repeated frm the prject, illustrates the varius parts f the. The device has an analgue sectin and a digital sectin and bth use industry standard IC s. The analgue sectin has 4 analgue inputs and ne utput and the digital sectin is wired fr an ByVac This is much mre interesting. Again a standard L93 mtr cntrller IC is used. The chip needs its wn pwer supply via either K r K. The pwer t the mtr is smthed by C4 and C5 but, depending n the mtr used it can have an effect n the CPU if supplied by K t the pint f crashing it at mtr switch n. Page 7 f 0

8 Prduct Specificatin and Build Instructins This is the reasn fr the ptin f a separate supply n K in which case jumper must be adjusted accrdingly. The interface is intended t drive mtrs but it desn t have t, it can drive anything yu like within the specificatin f the chip. It is cnnected t the PCF8574 as fllws: 7 Rel ay 6 Rel ay 5 EN B 4 INB Out 4 3 INB Out 3 EN A INA Out 0 INA Out s and 5 are enable lines and are active high. Out t Out4 are the screw terminal utputs intended fr the mtr cnnectins. 7 Relay Frw ard Rever se 6 Rel ay 5 EN B 4 IN B Ou t4 3 IN B Ou t3 EN A IN A Ou t 0 IN A Ou t 0 0 Brake 0 0 Stp 0 X X Assuming that a mtr is cnnected t Out and Out the abve table shws the actins that the mtr will take. Of curse Frward and Reverse are a bit meaningless ther than they are ppsite t each ther. This table translates the utput int hex fr cnvenience. Hex 0 ENA INA INA Out Out Frward FEh 0 Reverse FDh 0 Brake FCh 0 0 Brake FFh Stp FBh 0 X X Experiment:. Optinally cnnect a separate pwer supply t K and adjust JP accrdingly. This is s we dn t get any pwer prblems at the CPU end.. Cnnect a small DC mtr t K4 (M), the vltage f curse shuld be similar t the pwer supply. Nte that if using pwer supplied by BV30, this is the raw unregulated pwer frm the mains adaptr s culd be in the regin f 9 t 0V. 3. Make the mtr g frward, CPOKE &7e &fe 4. Stp the mtr CPOKE &7e &fc, this may r may nt wrk depending n the mtr, try als CPOKE &7e &ff. The idea behind this is t supply a shrting acrss the mtr wires. 5. Make the mtr g backward, CPOKE &7e &fd 6. Write a prgram t d this in TCB The ther mtr utput wrks in exactly the same way and s there is n pint in repeating the experiment. A stepper mtr can be cnnected t bth mtr utputs and driven by sftware Analgue Output Referring t the data sheet fr the PCF859, there is a cntrl register that sets up the varius ptins fr analgue input and utput. The pertinent bit f the cntrl register fr analgue utput is bit 6, This enables the analgue utput if it is set t. The device address, assuming that the jumpers are nt present is 9Eh. Because the cntrl register needs setting as well as the data t be utput, CPUT must be used. Experiment:. Cnnect a meter t the analgue utput, pin 4 and grund, pin f K3. Type CPUT &9e &40 0 This will write 40h t the cntrl register ( bit 6 high) and then g n t write 0 as the analgue utput. Observer the meter reading. 3. Type CPUT &9e &40 &ff Nte that each time the cntrl register needs writing t, the meter reading shuld nw be arund +5V. 4. Just fr gd measure try CPOKE &9e &40 &80 This shuld set the vltage at arund.5v The abve shws hw t utput an analgue signal. Nte that is prbably better t keep the cntrl register in a variable thus: k=&40, CPUT &9e k &ff The variable k can nw be manipulated with AND and OR s as nt t affect the riginal cntrl bits. This is particularly imprtant if analgue input is used alngside analgue utput. ByVac Page 8 f 0

9 Prduct Specificatin and Build Instructins 9.6. Analgue Input There are many ptins fr analgue input but fr simplicity we will just lk at btaining data frm channel. The cntrl register needs setting up fr this but it nly needs t be dne the ne time, CPOKE will d this. Fr the purpse f this experiment I have cnnected an LDR (dark value abut 80k) t pin and 8 f cnnectr k3. As there are 00k pull up resistrs n the inputs I wuld expect t see abut V n pin and less than that in bright light. Experiment:. Cnnect an LDR as described abve, n my system this gives between 3.5V when I cver it with my hand and.9v in the light.. Type CPOKE &9e 0, this will write t the cntrl register, turn ff analgue utput and select channel analgue input. 3. Type CPEEK &9e a 4. Type CPEEK &9e b 5. Observe the value f A and B. Referring t the data sheet the cnversin result is nt available until the secnd reading dn t get caught ut by this. 6. Change the light falling n the LDR 7. Type CPEEK &9e a 8. Type CPEEK &9e a 9. Observe the value f A this shuld have changed. 0. On my system the values range frm abut 00 in the light t 00 when cvered. This is the circuit diagram f the set up used. The lamp is cnnected t relay, the fan t M and the thermistr t channel analgue in. As we are n a mre advanced prject, I will assume that yu have read the RTC Square wave utput text (stupid assumptin I knw). Multi tasking extlled the virtues f writing cde in a certain way, I will fllw that here Feedback System This is a cmplete prject using 3 elements f the system. Fr this yu will need a thermistr, a small lamp and a mtr with a fan (prpeller) attached. The thermistr is a small bead type, at rm temperature the resistance is abut 00k t 0K. When held by thumb and finger it rapidly reduces t abut 80k t 85k. The lamp is a trch bulb, I had a.5v trch bulb and a 5V supply s I put a R resistr in series with it. Fr the mtr I used an ld V cmputer fan, this wrked very well but it wuld nt reverse, just as well this is nt needed in this applicatin. The idea f the system is t warm the thermistr with a lamp and when it reaches a certain temperature, switch the lamp ff and cl it dwn with the fan. In this way the temperature is kept within limits. This culd be applied t real situatins and s frms an interesting experiment. Thermistr bulb and fan with breadbard. ByVac Page 9 f 0

10 Prduct Specificatin and Build Instructins Thermistr tuching lamp Variables A = Lamp n / ff, = n B = Mtr n / ff, = n C = Thermistr temperature value, high = ht, lw = cld D = Trigger value fr thermistr E = keep track f the utput value Here are the rutines that the abve variables use, r is that the ther way rund? Each rutine is respnsible fr its wn dmain. The cntrl rutine has a hysteresis that prevents the lamp and mtr frm ging n and ff t quickly. This is fixed at. Lamp Rutine rem lamp if a= then e = e and &bf if a<> then e = e r &40 CPOKE &7e e return This rutine will simply turn the lamp n r ff depending n the variable A. If A is then the lamp will turn n, anything else it will turn ff. Nte that variable E is used fr the cntrl register. Mtr Rutine rem mtr t turn mtr ff simply set enable bit high if mtr ging wrng way use &fa instead f &f9 if b= then e = e r &04 if b<> then e = e and &fb CPOKE &7e e return This is exactly the same as the lamp rutine except it uses variable B Main and Setup e=&fe initial utput value CPOKE &9e 0 set channel analgue i/p gsub 3000 print Current temp =, c input set trigger value, d 00 rem main lp gsub 000 gsub 000 gsub 3000 gsub 4000 gt 00 The main rutine first sets E which effectively sets digital utput start cnditin and als sets the cntrl register fr channel analgue input. The first gsub 3000 is simply t indicate t the user the crrect ball park fr determining the trigger value. The trigger value can be thught f as a temperature t set the system t. The main lp and in fact the way the prgram is written is as described in the Multi Tasking text. Thermistr Rutine rem thermistr CPEEK &9e c CPEEK &9e c return Nte here that the thermistr value is sampled twice, remember that the first sample is just the cnversin prcess, see the data sheet. All this rutine des is set variable C. Cntrl Rutine 4000 This cntrls the system is a cnstant used fr hysteresis 4000 rem cntrl if c>d+ then a=0:b= lamp ff mtr n if c<d then a=:b=0 return The cntrl rutine is respnsible fr setting A and B determined by the value f C and D. This is a screen sht f the running prgram, I set my trigger value t 35 as shwn Further The lamp culd f just as easily be cnnected t the mtr, M utput, just as in this case the mtr culd have been cnnected t a relay. Again lking at the data sheet, tw analgue channels culd have been used in cmparatr mde cmparing tw different inputs. ByVac Page 0 f 0