Heathkit ID 5001 4 Manual

Page 1

Advanced Weather
Computer
Technical Manual
Model lDA-5001-4

595-4245
Copyrlghl © 1988
HEATH COMPANY A,,:,;:::;::;:22
BENTON HARBOR, MICHIGAN 49022

Prlnted In the Unlted States of America

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Table of Contents

Introduction ........................................ 1-1
Specifications ...................................... 2-1
Digital Clock/4-Year Calendar ................................. 2~1
Wind Speed ................................................ 2-1
Wind Direction ............................................. 2-2
Thermometer ............................................... 2~2
Barometer ................................................. 2-3
General ................................................... 2-3
Relative Humidity Accessory (Model lDA-SOOl-l) ................. 2-4
Rain Gauge Accessory (Model IDA-5001-2) ...................... 2-4
Operation .................................. . . . . . . . . 3-1
FRONT AND REAR PANELS (controls, indicators, & connections) ...... 3-1
POWERUP OPERATION ....................................... 3-4
KEYPAD OPERATION ........................................ 3-6
Time ..................................................... 3-6
Wind ..................................................... 3-6
Rain . .................................................... 3-7
Rate ...................................................... 3-7
24 Hour ................................................... 3-8
Audio Warning ............................................. 3~8
Alert Warning .............................................. 3-9
Unit Selection .............................................. 3-9
Min/Max Funcljons .......................................... 3-9
Baud .................................................... 3-10
Display Intensity ........................................... 3-10
Display Angle ............................................. 3-11
Display Test .............................................. 3-12
RS-232C INTERFACE ACCESSORY (MODEL IDA-5001-3) ......... 3-13
Computer Interfacing ....................................... 3-13
RS-232C Operation Example ................................. 3-14

Serial Interface Commands ................................... 3-15

Page 3

Page IV

Normal Operating Characteristics ..................... 4-1
Circuit Description ....................... . .......... 5-1
1 15 VOLT SUPPLIES ......................................... 5-1
AC POWER .................................................. 5-2
5-VOLT SUPPLIES ............................................ 5-2
AC POWER DETECTOR, 60 HZ SWITCH, AND RESET SWITCH ..... 5-3
60-HZ CIRCUITS ............................................. 5-5
RESET CIRCUITS ............................................. 5-6
SYSTEM CLOCK ............................................. 5-7
THE ZS4COO (280C) CENTRAL PROCESSING UNIT ................ 5~8
MEMORY CIRCUITS ......................................... 5-12
Hardware ................................................. 5-12
Firmware ................................................. 5 -13
INTERRUPT OPERATION ..................................... 5-17
Interrupt Request/Acknowledge Sequence ....................... 5-17
Daisy Chain Architecture .................................... 5-17
Interrupt Priorities .......................................... 5-18
V.F. Converter Interrupt ..................................... 5-19
8.3 mS Timer Interrupt ...................................... 5-19
60 Hz Line Interrupt ........................................ 5-20
Wind Speed Intenupt ....................................... 5-21
RS-232C Receive Interrupt ................................... 5-21
RS-232C Transmit Interrupt .................................. 5-22
RS-232C Status/Handshake Interrupt ........................... 5-22
I/O PORT DECODERS ........................................ 5-23
WIND DIRECTION AND RAIN SENSORS PORT .................. 5-25
ANALOG SELECT PORT AND V.F. CONVERTER ................. 5-27
AUDIO TONE GENERATOR ................................... 5-29
BAROMETER ............................................... 5-30
HUMIDITY SENSOR ACCESSORY (MODEL-IDA-SOOl-l) ........ t. . 5-31
LIGHT SENSOR ............................................. 5-33
TEMPERATURE SENSORS .................................... 5-34
THE SYSTEM TIMER ........................................ 5-35
WIND SPEED SENSOR ....................................... 5-36
RS-232C INTERFACE ACCESSORY (MODEL IDA-5001-3) ......... 5-37
The 84C42 Serial [/0 Port .................................... 5-37
Serial I/O Drivers .......................................... 5-38
KEYPAD CIRCUITS .......................................... 5-39
DISPLAY CIRCUITS ......................................... 5-41

FLUORESCENT LIGHT CIRCUITS ............................. 5-45

Page 9

While this Book provides sufficient information to successfully troubleshoot the
ID-SOOl, you may want to study the ID-SOOl Operation Manual. part number
595-3736. This manual provides a complete description of all the commands,
detailed operating procedures. boom installation, and other information that
doesnt normally apply to bench testing the unit.

NOTE: The binder parts you received with this Technical Manual are

listed below.
PART NO QTY DESCRIPTION
5975175 1 1" binder cover
701-234 1 3-ring assembly

485-70 2 Binder fasten er

Page 1-3

Page 11

SPECIFICATIONS

DIGITAL CLOCK/4-YEAR CALENDAR

Displays ....................

Time Accuracy ...............

WIND SPEED*

Displays ....................

Gust Mode ..................

Average Mode ...............

Memory ....................

Accuracy ...................

6-digit, 12 or 24-hour format time readout;
6-digit date readout. AM-PM indicator in
12-hour format.

Determined by the accuracy of the AC line
frequency. No accumulative error; 003%
error with battery-backed clock during
power failure.

Two significant digits. Separate indicators
show if the display is in miles-per-hour,
knots, or kilometers-per-hour.

Instantaneous peak wind speed; memory
stores the date, time, and magnitude of
minimum and maximum gusts.

One minute wind speed average; memory
stores the date, time, and magnitude of
minimum or maximum average wind speed.

Date, time, and magnitude of minimum or
maximum gust or average wind speed.
Changes in last hour or last 24 hours.

:l: 5% or better.

' In conformance with the National Weather Service Federal Meteorological Handbook #9, Aviation
Weather Observation, Chapter AB, Sections 3 & 3.5, Specifications tor Supplementary Aviation

Weather Reporting Stations,

Page 24

Page 3-10

To recall the minimum value, press LOW and one of the following keys:
TEMPERATURE. PRESSURE. HUMIDITY, or WIND.

In either mode, you can recall TEMP. PRESSURE, HUMID, or WIND simply
by pressing the appropriate key. Recall indoor temperature or humidity by
pressing INDOOR key when in temperature or humidity min/max mode. To
remove one of these values, press CLEAR.

Press ENTER to exit.

To clear all minimum and maximum values, press ENTER and CLEAR keys
while in the normal mode.

BAUD

Selects the baud rate for the optional ID-5001-3 RS-232C interface. The hours
and minutes of the time display will show the rate.

Press BAUD key to choose baud rate. The default is 9600 baud. Continue to
press BAUD to step through 110, 150, 300, 600, 1200, 2400, and 4800. Press
ENTER to enter the rate and exit.

DISPLAY INTENSITY

Sets the upper and lower range of ambient light the lamp intensity control
circuits will respond to. To properly set these levels, the ambient light must be at
the high or low level limits that you expect to have when you are setting the
corresponding high or low backlit intensity.

Press and release ENTER and HIGH to set the upper intensity range. The
seconds display will show an intensity level between 1 and 32 (default is 32).
Press LOW to decrement this value, HIGH to increment. The lamp will darken
or brighten accordingly. Press ENTER to store the desired level.

Press and release ENTER and LOW to set the lower intensity range. The seconds
display will show an intensity level between 1 and 32 (default is 1). Press HIGH
to increment this value, LOW to decrement. The lamp will brighten or darken
accordingly. Press ENTER to store the desired level.

Note that you cant adjust the LOW level above the HIGH level and vice-versa.

Page 45

Pin 24, WAIT-Wait. When low, this input control line puts the ZSOC into a
wait state. Data, address, and control lines will remain in their current logic state
until pin 24 goes high. Typically, this line is used to synchronize the CPU to
slow memory and I/O circuits. Its not used in the ID-5001, so its tied high.

Pin 25, BUSREQ-Bus Request. This input is a control line thats used by
DMA circuits to gain access to the system bus. When low, the ZSOC halts
operation and its address, data, and output control lines enter a high-impedance
state. DMA isnt used in the ID-5001, so this line is tied high to ensure reliable
operation.

Pin 26, RESET-Reset. When brought low, this input control line halts all
CPU operation. It disables interrupts and sets the interrupt mode to zero. The
program counter, interrupt vector register, and refresh registers are cleared.
During reset time, the address and data bus go to a high-impedance state, and all
control output signals go high. No memory refresh occurs. Note that the reset
line must be held low for at least three clock cycles to allow the Z80C to
properly initialize its internal registers. In the ID-5001, pin 26 is held low for
about 250mS at powerup to give the clock oscillator time to start up. If the reset
line was allowed to go high before the clock pulses started, the Z80C would lock

up.

Pin 27, m - Machine cycle one. This output line pulses low when the ZSOC is
fetching an instruction from memory. The pulse occurs during the first half of
the M1 cycle when the instruction is fetched. During the second half of the M1
cycle, the Z8OC is internally processing the instruction and doesnt need to
access the bus. Its during this time that a memory refresh takes place.

Pin 28, RFSH-Refresh. This output control line goes low during the second
half of an M1 cycle to inform external circuits that a dynamic RAM refresh is
taking place. During this time, the rest of the 280C is internally processing an
instruction and does not need to access the busses. Instead, the ZSOC places the
contents of the refresh register on A0-A6 and pulses MREQ. External circuits
decode these lines to perform a memory read to refresh the RAM. (Note that
theres no data transfer, however.) This results in a transparent refresh and
eliminates the need of arbitration logic, which would otherwise slow down
system operation. Since the ID-SOOl uses static RAM, this line isnt connected.

Page 5-11

Page 53

Page 5-19

U414 internally sets its own priorities. Port A is higher than B and, within each
port, the receiver is higher than the transmitter. The handshake lines and internal
status registers share the lowest position. This results in the revised priority

table.

Priority M Function

Highest OTC-0 V.F. Convener Counter
OTC-1 5.3 m3 Timer
OTC-2 Baud Rate Generator
OTC-3 Wind Speed Counter
DCDA 60 Hz Line Counter
RXDB Receive Data port B
TxDB Transmit Data port B

Lowest --- Status Registers/Handshake Lines

*The OTC-2 input no longer generates an interrupt request.

The following paragraphs briefly describe what takes place during the interrupts.

V.F. CONVERTER INTERRUPT

The V.F. converter is hard wired through U408D to the counter zero input
because its generating the highest-frequency pulses (4000Hz/V). This requires
that the CPU respond to it the fastest so that data wont be lost. Thus, the
program that handles this interrupt just takes enough time to increment a location
in RAM that indicates the interrupt occurred. Its up to other programs in ROM
to process the data. Some of these are in the 8.3mS timer interrupt handler.

8.3 m8 TIMER INTERRUPT

The 8.3mS timer is the only circuit in U412 that isnt externally connected. Both
the input at pin 22 and the output at pin 8 are open. In addition, it is the only one
that is programmed as a timer. The others are event counters and dont increment
their internal registers until a negative-going pulse occurs on their trigger inputs.
At powerup, however. the CPU monitors the AC line frequency present at
U412-21 and then programs the 8.3mS timer to automatically generate an
interrupt request at twice the line frequency. (For SOHz systems, this would of
course be called a IOmS timer.)

Page 55

After modifying the memory location, the program updates the clock/calendar
RAM locations. This results in the front panel display clock being synchronized
to the power line frequency, which has a better long-term accuracy than the
built-in crystal oscillator. If power had been lost, the SmS timer intenupt
program would take over clock maintenance and use the 2.4576MHZ system
clock as a time base. This, however, is accurate enough for the few hours that
AC power is down.

After updating the clock, the program exits the routine.

WIND SPEED INTERRUPT

Sinusoidal pulses from U406F-12 in the wind speed circuits connect to counter
#3 in the CIC through U412-20. This counter doesnt have a direct output, but
can pulse the interrupt line.

When the CPU processes the wind speed interrupt, it increments the contents of
a memory location in U416 then exits the routine. The next time the Z80
processes an 8.3mS timer interrupt, it compares the current count with a previous
count to determine wind speed.

RS-232C RECEIVE INTERRUPT

When the optional IDA-5001-3 RS~232C Accessory* receives a serial byte from
the external terminal, the accessory converts the byte to parallel, pulses the
interrupt line, then waits for the CPU to respond. When the 280C processes the
serial port receive intenupt, it reads the byte from U414 and stores it in a buffer
in RAM for further processing later. The CPU then checks the buffer to see if its
about to overflow. If so, the CPU immediately sends a control-S to the terminal
to stop the flow of data until the 280 gets time to process whats already been
received.

" Standard with wired units.

Page 5-21

Page 75

DISPLAY CIRCUITS

The display circuits are designed around three HD61604 surface-mount LCD
driver ICs and a custom liquid crystal display. Refer to the display driver
schematic and display schematic board as you read the following.

LCDlOl on the display board was designed by Heath Company but is custom
manufactured for Heath by Toshiba. Its a back-lit display with front and rear
polarizer films that keep it opaque until a potential difference is applied across
one of the two backplanes and the appropriate segments to be lit. As with most
LCDs, the backplane voltage and segment voltage are pulsing between zero and
+ 5 volts and are 180° out of phase. This effectively places an AC signal across
the electrodes and thus prevents damage to the DC-sensitive liquid crystal.

Because there are so many segment on the display, the Weather Computer uses
HD61604 display drivers to multiplex the segment data being sent to the display.
These ICs are located at U201-U203 on the driver board and do most of the work
interfacing the ZSOC to the LCD. The pins on the computer-side of these chips
consist of an input-only data bus, D0-D7 at pins 1-10 and 12-15, a READY
handshake line at pin 2, chip-select and write/read lines at pins 3-5, and some
special control lines at pins 16-22. 78, and 80. LCD control lines consist of two
backplane-select lines at pins 23 and 24, and 51 segment drivers at pins 27-77.

The ground return is at pin 11 and VCCB supplies +5 volts at pin 1. Since the
battery-backed supply is used, the chips remain active during an AC power
failure. (You can verify this by removing the light shield on a battery-backed
unit and shining a strong light behind the LCD. You ll be able to see segments
for the functions that hadnt been shut down-the time for example-still
working.) Since these chips typically draw less than lOOuA, its easier to let
them keep running rather than add the cost of standby circuits or extra code to
reprogram them after each power failure (which would be necessary if they were
connected to VCCA).

The oscillator at U204A and U204D generates the internal timing for the driver
ICs. C207, R203 and R204 set the frequency to about l25kHz. The output at
U204D-11 connects in parallel to pin 80 of U201-U203 to clock the three chips.
To make sure the chips operate in phase, the CPU pulses the SYNC line at
U204B-4 (from U4l7-13 on the main board) several times at powerup. The high
on this line connects in parallel to pin 78 of each driver and resets the internal
registers so that they start at the same count. From then on, the drivers do not
require resynchronization, so the CPU won't pulse U204B-4 again unless AC
power is momentarily lost and the backup battery isnt installed.

Page 5-41

Page 123

Refer to Pictorial 8-3, "Calibration Iube Setup," as you perform the following.

NOTES:

1.

In the following steps, it is important that you do not get any water
inside the pressure transducer. Therefore, he sure to place the
Weather Computer higher than the top of the water level.

The purpose of the calibration hose (medium clear tubing), which
you will use in the following steps, is to cause a change in the
pressure that is equivalent to a two-inch drop in a mercury column.

0 Fill the calibration hose with 44 to 60 inches of water until you have a loop of
water 22 to 30 inches high, as shown. Tap the sides of the hose to remove any
air bubbles. Then clamp the hose in the top calibration clips, as shown. Pinch
the clips together to hold the hose in place, if necessary. Filling the hose with
hot water will remove any kinks in it and make it easier to work with.

NOTE: When you install the 5" tubing in the following step, be sure to push it
firmly onto the transducer port. Otherwise, air leaks will make it impossible for
you to calibrate the Weather Computer. Also. water will run out of the
calibration hose when you later reposition it on the fixture.

o If the Weather Computer has a single-port transducer similar to the one in
Detail A of the "Calibration Tube Setup" illustration, perform step 1 below.
Otherwise, perform step 2.

1.

Refer to. inset #2 in the illustration and slide 1/2" of one end of the
medium clear tubing over one end of the 5" length of small clear
tubing. Then out off the medium tubing so that it is even with the end
of the small tubing as shown.

Refer to detail A and slide the 1/2" end of the 5" length of small clear
tubing onto the transducer port.

Refer to detail B and slide either end of the 5" length of small clear
tubing onto the indicated port P1 of the two-port transducer.

0 Push the long end of the calibration tubing into the 5" length of tubing that is
already installed on the transducer.

Page 8-9

Page 137

SETUP

Perform the following setup procedure if you are servicing a problem in the
display circuits. Refer to "Disassembly" and to Pictorial 9-3. the "Display Driver
Assembly Setup" illustration, as you perform these steps.

Remove the two sets of hardware holding the main circuit board to the
brackets.

Lift the main circuit board until S401 and S402 unplug from P205 and P204
on the display driver board.

Unplug S302 on the power supply circuit board.

Temporarily remove the front panel.

Remove the display driver assembly and set it down in front of the chassis.
Loosely reinstall the front panel onto the chassis so you can use the keypad.
Plug the display driver extension cables into S401 and 5402.

Route the cables under the power supply circuit board and through the front
panel display opening.

Connect the free ends of the display driver extension cables to P205 and P204
as shown. Make sure that the plugs are not offset by one pin.

Connect the fluorescent lamp to S302 through the lamp power extension
cable. Route the cable over the top of the front panel and away from the
display driver extension cables to reduce the effects of noise.

The Weather Computer is ready for servicing. You can now easily reach both
sides of the display driver circuit board with a test probe.

Page 9-5

Page 169

Keypad Circuits Waveforms

Without pressing a key, you should see the following waveforms on the outputs
of U406 on the main circuit board. If not, check U406, U411, and U417. Also
make sure that VCCA is present at RP402. Note that the duty cycle of the
waveforms depends on the ambient light levels. This is because the keypad

circuits are at the same port address as the lamp control circuits.

If you press a key, the waveform will widen by about IOOuS as the Z80 senses
the keypress and sends a scanning signal through U406. If not, check the keypad,
RP401, and U409.

I fTT-;.[.

Lifl <

, .
in . i
llama-2 1 l
(synchronizing Signal) » ! l
v - 2.0 With: l t 1 i l
H = 5 ins/div l-w-J. -, I
Baseline in division 5 1W
I i Z
Mus-b m
l

v = 2.0 v/div
it = 5 ins/div

Buseline 3L divisisn l

f

T

mos-2
(Synchrnnizing signsl)
v = 2.0 V/div

ll - 5 mS/div

Baneline n! diusion s
"Ans-6

v - 2.0 V/div
u = 5 ins/div

Baseline s: divisisn l

Page 9-37

UADEZ

(Synchronizing signal)
V ' 2.0 V/div

1-1 - s sis/div

unselins It diviiisn 5

406-8

v = 2.0 V/div
H = 5 ins/div

Baseline at division 1