City #25 16 августа 1999

Железо

Iron - a simple diagram of the analog-digital converter, which allows to digitize Analog signals from the 10 / 8 bit quality.

  *********** *********** PLANET SHELEZYAKA



(C) V. Kazakov


  Decided to publish this old article from the ON LINE
# 27, because he himself from time to time back to
this topic. Even assembled and offer shemku
connected to the computer, but due to lack of chip ADC (socket 
is empty) so far and do not try it at work. Also addressed to 
the LDE with asking for help in buying chips and software

for this device, but unfortunately, the answer and
could not wait. So make no mistake about
proposed later in this article addresses and phone Dennis. 
Perhaps, with time everything has changed. 

  And yet. If you believe the advertising V.M.G. in ZX Power # 1
2 (and why, in fact, she did not believe), they developed a 
scheme for ADC only four nedifitsitnyh and inexpensive chips 
and he can send it for a certain amount for everyone. By the 
way, and the software under She has - the program Digital 
Factory. Somewhere year Pasha sent him back the money after a 
month they returned. Too bad .... 

  Article printed without abbreviations.

(C) LDE SOFT


   Before you simple diagram of analog-digital
converter, which allows to digitize
Analog signals from the 10 / 8 bit quality.
Despite the simplicity of the scheme, money obtained
otsifrovok comparable quality otsifrovok received
computers IBM / PC or AMIGA, and often
surpasses it.

   But what to do with these tsifrovkami? I think,
Today, a lot of talk is not necessary,
recall only briefly: a manufacturer DIGITAL
tools for such well-known musical
Editors, like: DIGITAL STUDIO, SAMPLER,
INSTRUMENT, DMM, etc. And of course, the original
design their programs and megadem. But those who
ADC understands the word not only as a toy, capable of
record music or voice into a computer,
provided great opportunities for
experiments with analog signals. For example,
using a simple driver, ADC can be
turned into a digital oscilloscope, frequency counter,
voltmeter, multimeter, etc.

   Let's move on to describe the connection to the ADC
SPECTRUM'u. To connect, I decided
use free ports AY-3-8910 although it is possible
use any of your existing ports (eg
VV55, with even simpler software
management of ADC). Now specifically to the scheme: for her
assembly need to buy at Mitinskoe radio market
K1113PV1A chip and one (1) resistor.
Connects the ADC 15-th wires (12, 10, 16, 14 -
food), 2-9 ADC to 21-14 AY-3-8910, 17 / D to 7 AY,
ADC 18 to 12 AY, an ADC to 11 AY, ADC 11 to 13 AY.
Further, the scheme is clear.

   Now it's time to describe the bit-ports
with ADC and write your own driver.
Port AY "A" is for receiving bytes from the ADC on the bus
data. Port "B" is designed to receive two
ADC LSBs (You may wish not
use), acceptance of the ADC signal readiness
Reset / ADC.

   More information about the layout of bits in the port "B": 
bits 0 - quenching / transformation 
(0-gashenie/1-preobrazovanie) Bit 6 - Willingness ADC (0-READY) 
bit 1 - Junior bit ADC (D0 / D) bit 2 - the first digit of the 
ADC (D1). Such a strange layout of bits are random, so

easier to program the ADC. In addition, treatment
two LSBs ADC requires a lot of cycles
Z-80, which is already not enough, so they are withdrawn
I have a separate port, and you get to decide
use them or not. Personally, I have them
reserved, and I'm quite happy with an 8-bit
Quality otsifrovok.

   Management Features ADC: Conclusion 15
designed to select the conversion.
Let me explain: if the pin 15 logic 0, the ADC
operates in unipolar mode. To switch the ADC
in bipolar mode output 15 should be free.
Control signals: Conclusion 11 / D:
suppression / signal conversion. Controlled by bit 0
Port "B" AY. Has the following values: 1-quenching
0-conversion. After receiving the signal
ADC starts converting
analog signal to digital form by
successive approximation. Therefore, the digital code
at the ADC output comes with a slight delay:
about 30mks or about 11 cycles Z-80. Need
take into account this fact, or to interview ADC
a signal of readiness (17 ADC output, or 6 bits
Port "B" AY). When a logical 0 on this conclusion
ADC is ready and you can shoot bytes on the data bus.
After the ADC generates a signal "ready" to
assume bytes of RAM, and then reset the ADC
(See above) and give a signal conversion. Otherwise, the
ADC output will sit the old byte and you fill
RAM with just one digital readout.

   Oh, I forgot to remind that, for the ADC
should be -15 (or, at worst, -12) volts,
Recalls also that the power supply from IBM are
voltage is.

K 7N / AY


                K1113PV1A

K 12n/AY 18 D0 __ 17
K 11n/AY a D1 DR <Login
K 21n/AY 2 D2> 0 <15 R1-4, 7k
K 20n/AY 3 D3 0VA 14
K 19n/AY 4 D4 AI 13
K 18n/AY 5 D5-U2 12 <-15c
K 17n/AY 6 D6 + U2 10 <+ 5c
K 16n/AY 7 D7 0VD 16