[introduction] in processor pilot system, the clock speed of power comsumption and processor becomes direct ratio. If the computation on processor is laden very small, major power can be wasted. Go to processor speed modulation as far as possible slow frequency, the lowermost computation ability that holds job of executive at hand at the same time can reduce this kind of waste. This applied note described use DS1077 to be controlled through control of PC lead plane 8051 model the clock speed of microprocessor.

In processor pilot system, the clock speed of power comsumption and processor becomes direct ratio. If the computation on processor is laden very small, major power can be wasted. Go to processor speed modulation as far as possible slow frequency, the lowermost computation ability that holds job of executive at hand at the same time can reduce this kind of waste. This applied note described use DS1077 to be controlled through control of PC lead plane 8051 model the clock speed of microprocessor.

Introduce

DS1077 is oscillator of solid state CMOS, can produce 8kHz the frequency 33.2MHz to 133kHz. It can use as the independent oscillator of fixed frequency, or use as dynamo of processor pilot frequency. The frequency that two synchronous oscillators output can be adjusted by the user, child multiple gives priority to frequency through using two piece on but process designing beforehand scale down implement with scale down implement. Frequency and mode are installed but ” instant ” configuration, use 1077 lines serial interface memory is in EEPROM, this interface can be on bus line of a 2 lines can accommodate 0 DS1 at most. Two numbers control an input, CTRL1077 and CTRL3 also are to be able to control frequency or mode. In addition, DS1077L is the DS87 of 4V version, can produce 66.66kHz the frequency to 3.5MHz. Unless have additionally,explain in others, otherwise the 1077V of DS1077 and V version all consult as DS<> .

This application takes notes the use example illustrate DS1077. Does the use method that reveals DS1077 replace crystal to be 8051 small controller and tiny chip PIC to offer clock? Small controller. If where,this application notes still will explain odd many DS2 are used on 1077 lines bus line. Finally, give typical examples 8051 include firmware, how to achieve 2 strings in order to reveal advocate station and the exemple Cheng that lower level corresponds with every DS1077 on bus line.

Systematic overview

Pursue the system that 1 medium referenced principle graph showed to two become independent each other. Frequency of two systems work arises by DS1077. Give typical examples is here medium, although every system is independent at them by a common 2 lines advocate accuse implement control. This 2 lines advocate the system that the one part that the station can be older lead plane needs to control its subsystem. Advocate the subsystem that the station can decide to reduce working frequency not to need at present, in order to save electric power, quantity of heat decreases below certain circumstance, reduce electromagnetism interference possibly perhaps even. Use DS1077 to be able to avoid sometimes high frequency the clock that runs whole and large system, be like the clock on backboard. Distribute get much low frequency relatively easily with safety 2 lines bus line. Same, also can imagine use DS1077 to reduce a system. Working frequency is not small controller (a lot of miniature processor can reduce its speed enter low n even current Morpheus mode) , because DS1077 can reduce the frequency of whole system, is miniature not just alone. The place on put together is narrated, the application of use DS1077 may be very big very complex, but for this, application may be very complex. In using note, graph of principle of give typical examples already simplified greatly, aim when to explain. It showed the many DS1077 on public bus line, also showed DS1077 is OK and direct drive the small controller of a few popularity.

Use DS1077 regards a system as clock

In consulting the principle pursues, u1 (DS1077Z-125) use at generating U3 (8051 small controller. Those who be used at developing the firmware that discovers in appendix A is specific the 8051 working frequency that are DS87C520.DS87C520 are as high as 33MHz. Because U1 is 125MHz version,be in DS1077, OUT0 can produce 125MHz, 62.5MHz, 31.025MHz and 15.625MHz only. Although if our application needs to be mixed amain only,this is met half fast (the DS1077 of use 66MHz version) , that was no problem, but same, to the development of firmware, the hope runs small controller kilohertz range all the time. OUT0 does not have scale down implement, only one is divided with 1, 2, 4 or of 8 beforehand scale down implement. On the other hand, besides beforehand scale down implement besides, OUT1 still has a scale down implement, can divide frequency further with 2 to 1025. Accordingly, chose OUT1 to be 8051 time. Next, OUT0 still can be used at offerring clock for other component of the system. For simple for the purpose of, did not use CTRL0 and CTRL1, close with GND photograph however couplet. Ask an attention however, if use CTRL0 and CTRL1 input to ban,input, must save electric mode carefully, because the crystal of small controller is inputted,float can bring about needless oscillation or wrong clock.

Graph 1. Consult the principle pursues.

The 2nd system that institute of referenced principle plan shows is U2, DS1077 brings a foot to offer clock for the OSC4 of U1. PIC small controller. Same, DS1077 replaces fixed frequency crystal. The thing prophet situation that uses here agrees with give typical examples to be able to work in the frequency that is as high as 20MHz, accordingly like 8051 give typical examples, use OUT1 with the 2-1025 scale down that use implement, offer by OUT1 only. OUT0 but by the system. But, if did not use either output, because this did not join, well-advised practice is to ban with use corresponding CTRL to cite a base untapped output. This will be brought about supply reduce electric current apparently, and reduce needless EMI radiant possibility. Although, like 8051 systems, simple sex CTRL0 and CTRL1 were not used and ground connection.

As usual, it is very important to offer enough solution Ou. Same, important is to go Ou capacitance C1 and C2 have good high frequency performance, and physical position is very close use short PCB to take a line as far as possible, make every DS1077 takes a line.

The advantage of crystal of use DS1077 excel

DS1077 is likely excel crystal has a few main reasons. One, DS1077 frequency can be changed. Actually, it can be changed immediately, can ban even with. Next, DS1077 offers two-way, synchronism, but alone pilot output. In addition, the circuit when DS1077 need not use mixed and disorderly gasoline tank crystal to leave the job in one of its overtone frequency (the crystal to prep above 30MHz) . Finally, DS1077 compares crystal more be affected oscillatorily not easily.

Control DS1077

DS1077 can be used at securing frequency application and frequency conversion application. In applying below fixed frequency, do not need 2 lines advocate station, CTRL input is optional. But be inputted to needing to control frequency or mode, CTRL and / or 2 lines advocate the application of the station must be used according to wants flexibility.

CTRL0 and CTRL1 are inputted

If apply need to indicate DS1077 to enter,close mode in order to save the sources of energy, if apply a program to want,perhaps shut (3 condition) oscillator output, must use CTRL0 and CTRL1. Although do not have specific 2 lines to the command enters the mode that omit report or be banned,use output, but have a few skill that can finish in firmware in order to achieve same result. For example, be being inputted when CTRL is to be below foregone condition, can be installed or in cleared MUX register corresponding, with open and shutting needs function.

2 lines interface

When application need is generated except 1, 2, 4 or when the 8 frequency beyond, criterion 2 lines interface is indispensible. Very as simple as the interface that has 2 lines bus line. Need join SDA and SCL only (with GND) . Ensure bus line somewhere is included resistance is helped on bus line. These are the R1 in consulting the principle pursues and R2. Although 4.7k Ω resistor was used in this exemple, but the likelihood needs to undertake adjustment according to bus line. Amount of facility of capacitance, total on-line and want communication rate. But, 4.7k Ω can apply to process of great majority application. If do not have existing bus line, can use miniature to establish a bus line. The firmware of give typical examples of 8051 small controller was offerred in appendix A. In addition, if 2 lines interface won’t be used in application, ensure SDA and SCL bind the logistic n that decides specific definition, is not to leave float.

Ask an attention, in this exemple, there are many DS1077 on same bus line. For 2 lines advocate station to correspond alone with every DS1077, every DS8 needs to have an only address. 3 register in bus line allow bus line to go up to join at most at the same time 1077 DS1. U000 is for the address by process designing ” 2 ” , and U001 is for the address by process designing ” 2 ” . About the give typical examples that 1077 lines correspond, the firmware that ask referenced DS1077 or lists in DS<>L data data and appendix A.

DS1077 controls 2 lines lead plane

Read here, people may want to additional 2 lines are used in knowing why to apply in give typical examples advocate station. Correspond with DS1077 when the 2 lines agreement that two careful small controller can generate place to need. Although can be accomplished, but very dangerous, must take care all the more. The first all, when the frequency of small controller produces change, the sequential of Cheng of 2 lines exemple also can produce change. In addition, resemble be being mixed to 8051 give typical examples PIC give typical examples, certain small parts of an apparatus may have norms of lowermost job frequency to add the biggest frequency. Finally, ban using output is impossible, because small conference times no longer, because this can no more issue an order with enabling an oscillator afresh. But if must be done so, the data watch that checks the small controller that using is very important.

Firmware

The firmware that is based on the system of 8051 is included in appendix A. The layer exemple Cheng that it aims to reveal a need of inferior give typical examples and DS1077 communication. But, ask an attention, firmware implemented open loop system. Closed circuit is very specific at using a program. But correspond to show give typical examples and DS1077, the open loop give typical examples that is based on menu is beneficial. Program of terminal of a PC is to be used at issueing DS1077s order. Can search a command in firmware next with accurate examine what carrying out. Basic menu commands as follows:

Read the DS1077 that takes make choice of to show register
Edit multichannel answer to use a word
Edit DIV word word
Edit bus line word
Write DS1077, the address is ” 000 “
Write DS1077, the address is ” 000 “
Write DS1077, the address is ” 001 “
Write DS1077, the address is ” 001 “
Change firmware address of 2 lines communication

Because DS1077 installs memory to be in EEPROM, because this DS1077 electrify is in to memory,EEPROM is worth mediumly. Can use corresponding menu to command the cost that keeps MUX, DIV and BUS register. Menu commands 2 showed the give a demonstration that how carries out 2 lines to be written to the firmware of 8, and menu commands 1 show 2 lines are read take. Finally, menu commands 9 showed how to change 2 lines address, this address will be solved.

It is below keep 1234h DS1077 address ” 000 ” the give typical examples of DIV register:

LCALL START2WIRE; 2-WIRE START

   MOV A, #0B0H; DEVICE IDENTIFIER, SLAVE ADDRESS, WRITE
   LCALL WRITEBITS; SEND COMMAND BYTE
   LCALL ACKSLAVEWRITE; CHECK FOR SLAVE ACKNOWLEDGE
   MOV A, #01H; ACCESS DIV COMMAND
   LCALL WRITEBITS; SEND COMMAND BYTE
   LCALL ACKSLAVEWRITE; CHECK FOR SLAVE ACKNOWLEDGE
   MOV A, #12H
   LCALL WRITEBITS; SEND MSB
   LCALL ACKSLAVEWRITE; CHECK FOR SLAVE ACKNOWLEDGE
   MOV A, #34H
   LCALL WRITEBITS; SEND LSB
   LCALL ACKSLAVEWRITE; CHECK FOR SLAVE ACKNOWLEDGE
   LCALL STOP2WIRE; 2-WIRE STOP
   To Write The Same To The DS1077 At Address ‘ 001 ‘ , simply Replace:
   MOV A, #0B0H; DEVICE IDENTIFIER, SLAVE ADDRESS, WRITEWith The Following:
   MOV A, #0B2H; DEVICE IDENTIFIER, SLAVE ADDRESS, WRITE

It is below in the address ” 1077 ” DIV register place reads the give typical examples that takes DS000.

LCALL START2WIRE; 2-WIRE START

   MOV A, #0B0H; DEVICE IDENTIFIER, SLAVE ADDRESS, READ
   LCALL WRITEBITS; SEND COMMAND BYTE
   LCALL ACKSLAVEWRITE; CHECK FOR SLAVE ACKNOWLEDGE
   MOV A, #01H; READ DIVREG COMMAND
   LCALL WRITEBITS; SEND COMMAND BYTE
   LCALL ACKSLAVEWRITE; CHECK FOR SLAVE ACKNOWLEDGE
   LCALL START2WIRE; REPEATED 2-WIRE START
   MOV A, #0B1H; DEVICE IDENTIFIER, SLAVE ADDRESS, READ
   LCALL WRITEBITS; SEND COMMAND BYTE
   LCALL ACKSLAVEWRITE; CHECK FOR SLAVE ACKNOWLEDGE
   LCALL READBITS; READ DATA FROM DS1077 A
   MOV DIVDATAMSB, a; SAVE MUX MSB TO A VARIABLE
   LCALL ACKSLAVEREAD; ACK SLAVE SO WE CAN READ NEXT BYTE
   LCALL READBITS; READ DATA FROM DS1077 A
   MOV DIVDATALSB, a; SAVE MUX LSB TO A VARIABLE
   ;LCALL ACKSLAVEREAD; NO ACK – NO MORE TO READ
   LCALL STOP2WIRE; 2-WIRE STOP

Conclusion

DS1077 can replace crystal normally, when needing bigger flexibility and control. In addition, DS1077 still can be used at generation to arrive from KHz limits the wide range frequency of KHz. 133 megahertz. Control an amount according to what what need, it can move independently, also can use 2 lines interface by processor control. Although circuit of give typical examples is very simple, but it revealed DS1077. The consideration uses DS1077 in the next application.

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