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MICRO

PROCESSOR

13

11/2002

Elektor Electronics

select) input of the chip allows the signals
applied to the datalines to be programmed at
the location (address) pointed to by the
address bus. A Low input level applied to the
OE (output enable) input enables the con-
tents of the current address to be read out.
This is usually done immediately after pro-
gramming a byte, to make sure the program-

The EPROM

An EPROM is normally programmed
in a general-purpose EPROM pro-
grammer. Most of these units first
run a blank check on the chip you’ve
inserted. This is done by reading all
bytes in the EPROM to see if they
are at FF. If one or more bytes are
found with a different value, the
EPROM is not empty and a suitable
error report is produced. In many
cases, no further action is possible
until the entire chip is blank. Some
programmers are capable of detect-
ing the EPROM brand and type
inserted into the programming
socket. Once this information is
(automatically) established, the rel-
evant programming voltage(s) and
programming algorithm are set up.
Device recognition (if supported by

the chip manufacturer) is effected by
ap12 V to the A9 pin and
then reading certain addresses from
the EPROM.

Once the programmer has estab-

lished that the EPROM is empty, the
actual programming sequence is
allowed to begin. First, the EPROM
is switched to programming mode
by applying a relatively high voltage
to the V

pp

pin on the device. The

level of the programming voltage
depends on the EPROM type used,
and lies between 12.5 V and 21 V.
At the same time, the EPROM sup-
ply voltage (at the V

cc

pin) is raised

from +5 V to +6 V. If you are curi-
ous to know how that is done in
practice, look ahead at the top part
of Figure 4.

With the EPROM in programming

mode, a logic Low at the CS (chip

62256

IC3

A10

A11

A12

RAM

A13

A14

10

A0

A1

A2

A3

A4

A5

A6

A7

25

A8

24

A9

21

23

14

22

OE

20

CS

28

11

D0

12

D1

13

D2

15

D3

16

D4

17

D5

18

D6

19

D7

27

WR

26

9

8

7

6

5

4

3

2

1

74HCT245

IC5

3EN2

3EN1

11

12

13

14

15

16

17

18

19

G3

2

3

4

7

8

9

5

6

1

1

2

8x 10k

1

2

3

4

5

6

7

8

9

R9

+5V

+5V

A0

A1

A2

A3

A4

A5

A6

A7

A8

A9

A10

A11

A12

A13

A14

A0

A1

A2

A3

A4

A5

A6

A7

A8

A10

A11

A12

A13

A14

16V8

IC4

GAL

19

20

10

I0

I1

I2

I3

I4

I5

I6

I7

I8

F7

11

I9

12

F0

13

F1

14

F2

15

F3

16

F4

17

F5

18

F6

1

2

3

6

7

8

4

5

9

+5V

C3

100n

S1

R6

10k

S2

R5

10k

+5V

D2

4V7

R4

100

½

A9

D5

D4

R8

1k2

R7

1k2

+5V

D3

4V7

R3

33

½

D1

7V5

R1

10k

R2

10k

T1

BS170

+5V

K1

C1

100n

C2

100n

78L05

IC1

+5V

IC5

20

10

C4

100n

+5V

024066 - 11

RAMWRL

RAMOEL

RAMCSL

LED2L

LED1L

BUDIR

BUGATEL

EPOEL

EPCSL

EPVPPL

EPSV

HEADER

27256

EPROM

IC2

A10

A11

A12

VPP

A13

A14

10

A0

A1

A2

A3

A4

A5

A6

A7

25

A8

24

A9

21

23

14

22

OE

20

CS

28

11

D0

12

D1

13

D2

15

D3

16

D4

17

D5

18

D6

19

D7

26

27

9

8

7

6

5

4

3

2

1

+9V

DC

Figure 1. The circuit diagram of the EPROM emulator — exquisite simplicity.

Features

– Emulates 27C256 EPROM

– Suitable for programming with any pro-

grammer supporting the 27C256

– Electrical protection against reading of

DEVICE-ID

– Easy to erase

– Compact

– Easy to use

Содержание EPROM

Страница 1: ......

Страница 2: ...style plug that can be inserted in an EPROM socket The length of the umbilical cord is limited to prevent a too high capaci tive load on the data and address bus of the target system or timing proble...

Страница 3: ...voltage to the Vpp pin on the device The level of the programming voltage depends on the EPROM type used and lies between 12 5 V and 21 V At the same time the EPROM sup ply voltage at the Vcc pin is r...

Страница 4: ...ctronics 11 2002 IDENTIFICATION 024066 TYPE GAL16V8 PINS Pin assignment for input signals EPVP 8 Detection of 5V supply EPVPP 3 Low active detection of VPP 12V EPOE 1 Input for OE from EPROM socket EP...

Страница 5: ...s This IC is necessary while the emulator is in Blank mode when it is exptected to supply the value FF at all times dur ing a read command The GAL arranges for the driver to be acti vated in the direc...

Страница 6: ...CS VPP OE Data Data out unknown WR CS RD G DIR EPROM RAM BUFFER Data in unknown 024066 15 Figure 5 Signals in Normal mode C E L E K T O R 0 2 4 0 6 6 1 C1 C2 C3 C4 D1 D2 D3 D4 D5 IC1 IC2 IC3 IC4 IC5...

Страница 7: ...upply pin of the EPROM After all the voltage at this pin may become 6 V during programming which is not a healthy level for the ICs in the emulator If you do want to employ this voltage measures shoul...

Страница 8: ...object since the propagation speed of the waves and the rate of horizontal deflection time base were known This is how R A D A R came about an acronym that soon turned into an everyday word Subsequent...

Страница 9: ...car comes nearer and then decreases as the car trav els past you This effect is also noticeable in F1 Grand Prix races when the cars roar past the camera This phenomenon works the other way round as...

Страница 10: ...problem for the detector is the signal to noise ratio which doesn t get any better with Schottky diodes In this section the sen sitivity can also be improved through the use of aerials Whilst the fir...

Страница 11: ...dars the circuits are less sensitive to interference signals the frequency of the jamming signal therefore has to be as close as possible to that of the speed camera and every device has its own frequ...

Страница 12: ...ocols used can come in three different varieties In Europe the most common protocol is the ISO standard All of these protocols rely on serial data transfer but the Vehicle Diagnostics Adapter Interfac...

Страница 13: ...aud and does not offer a handshaking option for the RS232 interface In addition it is only able to communicate using the 10 4 kHz ISO 9141 Protocol This stan dard is the most common used by the majori...

Страница 14: ...to the driver s seat The shape and pinouts of the 16 pin connector has already been described in the previ ous article Card Diagnosis Systems Elektor Electronics October 2002 The circuit described her...

Страница 15: ...hreshold voltage to around 4 V instead of the standard 2 5 V for a CMOS input The effect of this is to improve noise immunity on the input and the stage gain speeds up signal transition times For the...

Страница 16: ...should be about one diode drop 0 4 to 0 6 V higher than the voltage measured at the TxD pin In the circuit diagram TxD is assumed as 9 3 V which then gives 8 9 V after the voltage drop across D6 Shoul...

Страница 17: ...1 Assuming that the interface is correctly connected you should see the four red LEDs light up and the following message will appear on the screen ELM323 v1 0 This gives the version number of the micr...

Страница 18: ...ng the installation paths For the device driver you will need the EZ USB Development Kit which you have USB Driver Programming 2 writing your own device driver By M M ller and C Ehmer In the previous...

Страница 19: ...ctly cheap The solution proposed here is to use freely already installed and used in Part 1 of this series Setup information Windows always needs an INF file for installing a device driver Such a file...

Страница 20: ...device driver Start Visual C Studio select Open Working Area from the File menu and open the file named MICROCONTROLLER 32 Elektor Electronics 11 2002 Figure 3 Testing the device driver in BinTerm Ta...

Страница 21: ...aths in the compiler and linker options must be modified accordingly If the code cannot be generated without errors or war nings the environment has not been configured properly Under C it is nearly i...

Страница 22: ...to MYSYS SYS Copy the modified INF file and EZUSB SYS to a diskette You have now produced a driver diskette for a Cypress IC with the VID and PID numbers you have defined Connect the USB device having...

Страница 23: ...The solution was found in the S88 bus This controller interface which is quite busy collecting return data via the track when PC control is used has precious little to do in stand alone operation Tha...

Страница 24: ...and large this circuit does the same thing as the simple version An 8 position switch is used once again to select the controller and even the pushbutton switch is still present although here it is hi...

Страница 25: ...tand This trick is performed by two 4 bit binary full adders type 4008 whose operation we will not attempt to explain here Suffice it to say that we have here is a sort of primordial computer IC The 8...

Страница 26: ...a switch before it can be programmed The super deluxe controller address pro grammer does not have these disadvantages and it allows the addresses of up to eight GENERALINTEREST 39 11 2002 Elektor El...

Страница 27: ...ard Figure 4 is designed to have K2 K3 and K4 fitted on the back side solder side so the board with the rotary switch and display can be fitted directly behind a front panel see Figure 5 EEDTS Pro key...

Страница 28: ...re shown in Figure 8 and Figure 9 The first one uses a relay with two electrically isolated make or changeover contacts If all of the contacts of the available relay are already being used the circuit...

Страница 29: ...put sensi tivities and limited output signal lev els can be mitigated by preceding the relevant line input with the con trol circuit that is described here The signal levels of 2 V that modern CD or D...

Страница 30: ...ecided to go for a relatively mature design Each channel consists of an input buffer and an adjustable amplifier stage There is a single indicator common to both channels In order to power the opamps...

Страница 31: ...d R20 so that both the negative as well as the positive half of the signal voltage is monitored Because the zener current is set to a really small value of only 1 mA the voltage drop across D5 is only...

Страница 32: ...o construction should not be hurried The terminals for the inputs and outputs are nicely grouped on one side of the PCB while on the oppo site side two SIL headers can be found for the connections to...

Страница 33: ...hears a cry When a cry is detected and persists for a given time it will dial out a pre pro grammed number typically the par ents mobile There is no need to answer the call a glimpse at the mobile s...

Страница 34: ...rence voltage REF The other input AIN0 is connected to the AF signal CMP and when this signal rises above the reference voltage the com parator output will switch and gen erate an interrupt in the mic...

Страница 35: ...adapter unit supplying 9 to 12 V provides power for the baby monitor A pro tection diode D5 ensures that reversing the power supply leads cannot damage the input C19 acts as a smoothing capacitor to...

Страница 36: ...uipped with a Pulse Width Modulated PWM output and this can do the job just as well This output has a resolution of 8 bits with a clock frequency of 19 6 kHz fCK 510 The dual sine waves are produced b...

Страница 37: ...e number is zero do not press S1 at all after tapping in the digit press S2 to enter it and move on to the next digit of the number Carry on until the complete number is entered and then a long press...

Страница 38: ...s order number 53 06 89 33 that has its existing window removed You can of course change the dimensions for use with a differ ent type of exposure box The parts The frames are made from two pieces of...

Страница 39: ...out of a piece of aluminium Figure 2 shows all the relevant dimensions the hole on the left fits over the stay peg This could have been a round hole but then this should have had the exact size of the...

Страница 40: ...s been found the sliders should be moved tightly against the pins The wing nuts are then tightened and the align ment is complete The protective films on the PCB should be removed in a dark room The t...

Страница 41: ...aterial as the anode and there recombine with the returning electrons and with oxygen from the air to form water This is known collectively as the membrane electrode assembly MEA Researchers at Motoro...

Страница 42: ...he output of the reformer Using the multi layer ceramic technology researchers have demonstrated an integrated vapouriser and miniature methanol steam reformer and a separate chemical heater three of...

Страница 43: ...chosen to use white LEDs instead of a halogen lamp Contrary to popular belief the efficiency of a white light LED is not much better than a low power tungsten bulb and in fact worse than higher watta...

Страница 44: ...lector arrange ment For the power source a lithium ion rechargeable battery has been cho sen These cells are more expensive than NiCds but offer a number of advantages A NiCd cell of the same capacity...

Страница 45: ...ister ADRES is given by Rearranging VBATT is measured every 100 ms to regulate the output power The microcontroller uses this battery voltage measurement to point to a stored look up table for one of...

Страница 46: ...that stock them Charge indication An important design feature of the torch is that the user should never be left unexpectedly in the dark It is GENERALINTEREST 61 11 2002 Elektor Electronics 012019 T1...

Страница 47: ...harge left in the cell the torch will function for 5 hrs at brightness level 4 or more than 12 hrs at level 5 so you should never be left completely in the dark The battery and coil The battery specif...

Страница 48: ...ount components and LEDs onto the boards The coil is the only conven tionally packaged component and should be soldered to the component side of the PCB The two PCBs are then soldered together at righ...

Страница 49: ...atterns and character sets You will also find many useful links leading to application examples and other sources of information Another address for information on this controller connection details o...

Страница 50: ...ience in this area may want to start off at an extensive description containing lots of photographs of an LCD connected to a printer cable on the Build your own printer cable LCD display 9 webpage pro...

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