Engr. Michael David - Hand-On Embedded System Architecture : Introduction to Robotics and the AVR Microcontroller Practical Guide For Students and Professionals

ngr. Michl Dvid ll right rsrvd. N prt f this wrk my b rprducd, strd in rtrivl systm, r trnsmittd in ny frm r mns, lctrnics, mchnicl, phtcpying, rcrding r thrwis withut th prmissin r cknwldgmnt f th uthr. Cntnts Cnclusin mbddd Systms Intrductin W cn brdly dfin n mbddd systm s micrcntrllr-bsd, sftwr drivn, rlibl, rl-tim cntrl systm, dsignd t prfrm spcific tsk. It cn b thught f s cmputr hrdwr systm hving sftwr mbddd in it. n mbddd systm cn b ithr n indpndnt systm r prt f lrg systm.

In this bk, w will xplin ll th stps ncssry t dsign n mbddd systm nd us it. This bk hs bn dsignd t hlp th studnts f lctrnics lrn th bsic-t dvncd cncpts f mbddd Systm nd 8051 Micrcntrllr. mbddd Systms - vrviw Systm systm is n rrngmnt in which ll its unit ssmbl wrk tgthr ccrding t st f ruls. It cn ls b dfind s wy f wrking, rgnizing r ding n r mny tsks ccrding t fixd pln. Fr xmpl, wtch is tim displying systm. Its cmpnnts fllw st f ruls t shw tim.

If n f its prts fils, th wtch will stp wrking. S w cn sy, in systm, ll its subcmpnnts dpnd n ch thr. mbddd Systm s its nm suggsts, mbddd mns smthing tht is ttchd t nthr thing. n mbddd systm cn b thught f s cmputr hrdwr systm hving sftwr mbddd in it. n mbddd systm cn b n indpndnt systm r it cn b prt f lrg systm. n mbddd systm is micrcntrllr r micrprcssr bsd systm which is dsignd t prfrm spcific tsk.

Fr xmpl, fir lrm is n mbddd systm; it will sns nly smk. n mbddd systm hs thr cmpnnts It hs hrdwr. It hs pplictin sftwr. It hs Rl Tim prting systm (RTS) tht suprviss th pplictin sftwr nd prvid mchnism t lt th prcssr run prcss s pr schduling by fllwing pln t cntrl th ltncis. RTS dfins th wy th systm wrks. smll scl mbddd systm my nt hv RTS. smll scl mbddd systm my nt hv RTS.

S w cn dfin n mbddd systm s Micrcntrllr bsd, sftwr drivn, rlibl, rl-tim cntrl systm. Chrctristics f n mbddd Systm Singl-functind n mbddd systm usully prfrms spcilizd prtin nd ds th sm rptdly. Fr xmpl: pgr lwys functins s pgr. Tightly cnstrind ll cmputing systms hv cnstrints n dsign mtrics, but ths n n mbddd systm cn b spcilly tight. Dsign mtrics is msur f n implmnttin's fturs such s its cst, siz, pwr, nd prfrmnc. Rctiv nd Rl tim Mny mbddd systms must cntinully rct t chngs in th systm's nvirnmnt nd must cmput crtin rsults in rl tim withut ny dly. Rctiv nd Rl tim Mny mbddd systms must cntinully rct t chngs in th systm's nvirnmnt nd must cmput crtin rsults in rl tim withut ny dly.

Cnsidr n xmpl f cr cruis cntrllr; it cntinully mnitrs nd rcts t spd nd brk snsrs. It must cmput cclrtin r d-cclrtins rptdly within limitd tim; dlyd cmputtin cn rsult in filur t cntrl f th cr. Micrprcssrs bsd It must b micrprcssr r micrcntrllr bsd. Mmry It must hv mmry, s its sftwr usully mbds in RM. It ds nt nd ny scndry mmris in th cmputr. HW-SW systms Sftwr is usd fr mr fturs nd flxibility. HW-SW systms Sftwr is usd fr mr fturs nd flxibility.

Hrdwr is usd fr prfrmnc nd scurity. dvntgs sily Custmizbl Lw pwr cnsumptin Lw cst nhncd prfrmnc Disdvntgs High dvlpmnt ffrt Lrgr tim t mrkt Bsic Structur f n mbddd Systm Th fllwing illustrtin shws th bsic structur f n mbddd systm Snsr It msurs th physicl quntity nd cnvrts it t n lctricl signl which cn b rd by n bsrvr r by ny lctrnic instrumnt lik n 2D cnvrtr. snsr strs th msurd quntity t th mmry. -D Cnvrtr n nlg-t-digitl cnvrtr cnvrts th nlg signl snt by th snsr int digitl signl. Prcssr & SICs Prcssrs prcss th dt t msur th utput nd str it t th mmry. mbddd Systms - Prcssrs Prcssr is th hrt f n mbddd systm. mbddd Systms - Prcssrs Prcssr is th hrt f n mbddd systm.

It is th bsic unit tht tks inputs nd prducs n utput ftr prcssing th dt. Fr n mbddd systm dsignr, it is ncssry t hv th knwldg f bth micrprcssrs nd micrcntrllrs. Prcssrs in Systm prcssr hs tw ssntil units Prgrm Flw Cntrl Unit (CU) xcutin Unit (U) Th CU includs ftch unit fr ftching instructins frm th mmry. Th U hs circuits tht implmnt th instructins prtining t dt trnsfr prtin nd dt cnvrsin frm n frm t nthr. Th U includs th rithmtic nd Lgicl Unit (LU) nd ls th circuits tht xcut instructins fr prgrm cntrl tsk such s intrrupt, r jump t nthr st f instructins. prcssr runs th cycls f ftch nd xcuts th instructins in th sm squnc s thy r ftchd frm mmry.

Typs f Prcssrs Prcssrs cn b f th fllwing ctgris Gnrl Purps Prcssr (GPP) o Micrprcssr o Micrcntrllr o mbddd Prcssr o Digitl Signl Prcssr o Mdi Prcssr pplictin Spcific Systm Prcssr (SSP) pplictin Spcific Instructin Prcssrs (SIPs) GPP cr(s) r SIP cr(s) n ithr n pplictin Spcific Intgrtd Circuit (SIC) r Vry Lrg Scl Intgrtin (VLSI) circuit. Micrprcssr micrprcssr is singl VLSI chip hving CPU. In dditin, it my ls hv thr units such s cchs, flting pint prcssing rithmtic unit, nd piplining units tht hlp in fstr prcssing f instructins. rlir gnrtin micrprcssrs ftch-nd-xcut cycl ws guidd by clck frquncy f rdr f ~1 MHz. Prcssrs nw prt t clck frquncy f 2GHz Micrcntrllr micrcntrllr is singl-chip VLSI unit (ls clld micrcmputr) which, lthugh hving limitd cmputtinl cpbilitis, psssss nhncd input/utput cpbility nd numbr f n-chip functinl units. CPU RM RM I/ Prt Timr Sril CM Prt Micrcntrllrs r prticulrly usd in mbddd systms fr rl-tim cntrl pplictins with n-chip prgrm mmry nd dvics.

Micrprcssr vs Micrcntrllr Lt us nw tk lk t th mst ntbl diffrncs btwn micrprcssr nd micrcntrllr. MicrprcssrMicrcntrllr Micrprcssrs r multitsking in Singl tsk rintd. Fr xmpl, ntur. Cn prfrm multipl tsks t wshing mchin is dsignd fr tim. Fr xmpl, n cmputr w cn wshing clths nly. ply music whil writing txt in txt ditr.

RM, RM, I/ Prts, nd Timrs cn b RM, RM, I/ Prts, nd Timrs ddd xtrnlly nd cn vry in cnnt b ddd xtrnlly. Ths numbrs. cmpnnts r t b mbddd tgthr n chip nd r fixd in numbrs. Dsignrs cn dcid th numbr f Fixd numbr fr mmry r I/ mmry r I/ prts ndd. mks micrcntrllr idl fr limitd but spcific tsk. systm hvir nd cstlir. xtrnl dvics rquir mr spc nd micrcntrllr-bsd systm thir pwr cnsumptin is highr. cnsums lss pwr nd tks lss spc. mbddd Systms - rchitctur Typs Th 8051 micrcntrllrs wrk with 8-bit dt bus. mbddd Systms - rchitctur Typs Th 8051 micrcntrllrs wrk with 8-bit dt bus.

S thy cn supprt xtrnl dt mmry up t 64K nd xtrnl prgrm mmry f 64k t bst. Cllctivly, 8051 micrcntrllrs cn ddrss 128k f xtrnl mmry. Whn dt nd cd li in diffrnt mmry blcks, thn th rchitctur is rfrrd s Hrvrd rchitctur. In cs dt nd cd li in th sm mmry blck, thn th rchitctur is rfrrd s Vn Numnn rchitctur. Vn Numnn rchitctur Th Vn Numnn rchitctur ws first prpsd by cmputr scintist Jhn vn Numnn. s rsult, th CPU ds n prtin t tim. s rsult, th CPU ds n prtin t tim.

It ithr ftchs n instructin frm mmry, r prfrms rd/writ prtin n dt. S n instructin ftch nd dt prtin cnnt ccur simultnusly, shring cmmn bus. Vn-Numnn rchitctur supprts simpl hrdwr. It l ws th us f singl, squntil mmry. Tdy's prcssing spds vstly utpc mmry ccss tims, nd w mply vry fst but smll munt f mmry (cch) lcl t th prcssr. Hrvrd rchitctur Th Hrvrd rchitctur ffrs sprt strg nd signl buss fr instructins nd dt.