Lesson 1. Logic in packages: 74HC00, 02, 04, 08, 32

After this lesson the library has five real chips — with the same pin names as in the datasheet — and an alarm runs on them: open the door while the alarm is armed — the alarm lights up and the buzzer sounds, and the alarm stays on until someone presses Reset.

1.1. The idea: a chip is a package with gates

Wozniak built the Apple I not from separate gates but from 74-series chips: one package holds four or six identical gates. The package has 14 pins, each with a number and a name:

• 1A, 1B are the inputs of the first gate, 1Y is its output; then 2A, 2B, 2Y and so on up to the fourth;
• pin 7 is GND, pin 14 is VCC: power. Our power is shared by all chips, so these pins are not there.

The letters in the name are the family: HC are modern CMOS chips. Inside they have exactly what we build from transistors: P and N pairs. The digits say what is inside: 00 — NAND, 02 — NOR, 04 — NOT, 08 — AND, 32 — OR.

1.2. The idea: free inputs go to ground

On a board often only one gate of four is used. The inputs of the others must not be left in the air: a CMOS input has no level of its own, it "floats", and the gate output jitters. The rule from every datasheet: unused inputs go to GND (or to VCC). The same in the simulator: a hanging input gives an undefined value.

1.3. The idea: a latch from one chip

Two NANDs from one 74HC00 connected crosswise make an SR latch: a zero on one input lights the output, a zero on the other clears it, and when both are ones the latch remembers the last state. That is how the alarm remembers.

1.4. Building

A new project. You need the gates NOT, NAND, NOR, AND, OR — from any kit of the series or lesson 0.

Step 1. Chip 74HC00 — 4 × NAND

Package pins from the datasheet: 1 1A, 2 1B, 3 1Y, 4 2A, 5 2B, 6 2Y, 8 3Y, 9 3A, 10 3B, 11 4Y, 12 4A, 13 4B; 7 — GND, 14 — VCC (our power is shared, so these pins are not there). Port name = pin name: double-click a port → 1A and so on.

Ctrl+G → name 74HC00. Legs: inputs 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B; outputs 1Y, 2Y, 3Y, 4Y.

Step 2. Chip 74HC02 — 4 × NOR

Package pins from the datasheet: 1 1Y, 2 1A, 3 1B, 4 2Y, 5 2A, 6 2B, 8 3A, 9 3B, 10 3Y, 11 4A, 12 4B, 13 4Y; 7 — GND, 14 — VCC (our power is shared, so these pins are not there). Port name = pin name: double-click a port → 1A and so on.

Ctrl+G → name 74HC02. Legs: inputs 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B; outputs 1Y, 2Y, 3Y, 4Y.

Step 3. Chip 74HC04 — 6 × NOT

Package pins from the datasheet: 1 1A, 2 1Y, 3 2A, 4 2Y, 5 3A, 6 3Y, 8 4Y, 9 4A, 10 5Y, 11 5A, 12 6Y, 13 6A; 7 — GND, 14 — VCC (our power is shared, so these pins are not there). Port name = pin name: double-click a port → 1A and so on.

Ctrl+G → name 74HC04. Legs: inputs 1A, 2A, 3A, 4A, 5A, 6A; outputs 1Y, 2Y, 3Y, 4Y, 5Y, 6Y.

Step 4. Chip 74HC08 — 4 × AND

Package pins from the datasheet: 1 1A, 2 1B, 3 1Y, 4 2A, 5 2B, 6 2Y, 8 3Y, 9 3A, 10 3B, 11 4Y, 12 4A, 13 4B; 7 — GND, 14 — VCC (our power is shared, so these pins are not there). Port name = pin name: double-click a port → 1A and so on.

Ctrl+G → name 74HC08. Legs: inputs 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B; outputs 1Y, 2Y, 3Y, 4Y.

Step 5. Chip 74HC32 — 4 × OR

Package pins from the datasheet: 1 1A, 2 1B, 3 1Y, 4 2A, 5 2B, 6 2Y, 8 3Y, 9 3A, 10 3B, 11 4Y, 12 4A, 13 4B; 7 — GND, 14 — VCC (our power is shared, so these pins are not there). Port name = pin name: double-click a port → 1A and so on.

Ctrl+G → name 74HC32. Legs: inputs 1A, 1B, 2A, 2B, 3A, 3B, 4A, 4B; outputs 1Y, 2Y, 3Y, 4Y.

Step 6. Alarm: power and inputs

Switches ARM — the alarm is on, DOOR — the door is open, WIN — the window is open; the Reset button is RESET.

Step 7. Open: 74HC32

OPEN = door OR window. One gate of four works; the inputs of the other three go to GND: a CMOS chip input must not hang in the air, otherwise the output "floats". The same on a real board.

Step 8. The alarm starts: 74HC08

TRIP = open AND the alarm is on.

Step 9. Inversion: 74HC04

A NAND latch is triggered by a zero, so TRIP and the RESET button are inverted: nTRIP, nRESET.

Step 10. Alarm latch: 74HC00

Two NANDs crossed — a latch: nTRIP = 0 lights ALARM, nRESET = 0 clears it. The alarm stays on even after the door is closed — until Reset is pressed.

Step 11. Ready: 74HC02

READY = NOR(open, alarm): lit when everything is closed and there is no alarm.

Step 12. Lamps and chime

Speaker — buzzer mode, tone 880: it buzzes while ALARM = 1.

1.5. Check

1. Press Reset: ALARM is off, READY is lit — everything is closed, no alarm.
2. DOOR = 1 (the alarm is off): READY goes out — the door is open, but there is no alarm. DOOR = 0 — READY is lit again.
3. ARM = 1 — the alarm is on. WIN = 1: ALARM lights up, the buzzer sounds, READY goes out.
4. WIN = 0 — the window is closed, but ALARM stays lit: the latch remembers the alarm.
5. Reset — ALARM goes out, READY is lit.
6. DOOR = 1 and Reset: the alarm does not go out — while the door is open, nTRIP holds the latch.

Lesson 1 paste (Cmd+I)

You need the gates NOT, NAND, NOR, AND, OR (lesson 0 or its paste). The paste is five chips and the alarm; set the Speaker by hand — buzzer mode, tone 880.

# Lesson 1 — logic in packages: 74HC00, 74HC02, 74HC04, 74HC08, 74HC32 and an alarm built from them.# Paste: Cmd+I into a project with the gates NOT, NAND, NOR, AND, OR (lesson 0). chip 74HC00 {  portIn(1A)  portIn(1B)  portIn(2A)  portIn(2B)  portIn(3A)  portIn(3B)  portIn(4A)  portIn(4B)  portOut(1Y)  portOut(2Y)  portOut(3Y)  portOut(4Y)  NAND(1A, 1B, 1Y)  NAND(2A, 2B, 2Y)  NAND(3A, 3B, 3Y)  NAND(4A, 4B, 4Y)} chip 74HC02 {  portIn(1A)  portIn(1B)  portIn(2A)  portIn(2B)  portIn(3A)  portIn(3B)  portIn(4A)  portIn(4B)  portOut(1Y)  portOut(2Y)  portOut(3Y)  portOut(4Y)  NOR(1A, 1B, 1Y)  NOR(2A, 2B, 2Y)  NOR(3A, 3B, 3Y)  NOR(4A, 4B, 4Y)} chip 74HC04 {  portIn(1A)  portIn(2A)  portIn(3A)  portIn(4A)  portIn(5A)  portIn(6A)  portOut(1Y)  portOut(2Y)  portOut(3Y)  portOut(4Y)  portOut(5Y)  portOut(6Y)  NOT(1A, 1Y)  NOT(2A, 2Y)  NOT(3A, 3Y)  NOT(4A, 4Y)  NOT(5A, 5Y)  NOT(6A, 6Y)} chip 74HC08 {  portIn(1A)  portIn(1B)  portIn(2A)  portIn(2B)  portIn(3A)  portIn(3B)  portIn(4A)  portIn(4B)  portOut(1Y)  portOut(2Y)  portOut(3Y)  portOut(4Y)  AND(1A, 1B, 1Y)  AND(2A, 2B, 2Y)  AND(3A, 3B, 3Y)  AND(4A, 4B, 4Y)} chip 74HC32 {  portIn(1A)  portIn(1B)  portIn(2A)  portIn(2B)  portIn(3A)  portIn(3B)  portIn(4A)  portIn(4B)  portOut(1Y)  portOut(2Y)  portOut(3Y)  portOut(4Y)  OR(1A, 1B, 1Y)  OR(2A, 2B, 2Y)  OR(3A, 3B, 3Y)  OR(4A, 4B, 4Y)} power(VCC)ground(GND)input(ARM)input(DOOR)input(WIN)button{label="Reset"}(RESET)74HC32(1A=DOOR, 1B=WIN, 1Y=OPEN, 2A=GND, 2B=GND, 3A=GND, 3B=GND, 4A=GND, 4B=GND)74HC08(1A=OPEN, 1B=ARM, 1Y=TRIP, 2A=GND, 2B=GND, 3A=GND, 3B=GND, 4A=GND, 4B=GND)74HC04(1A=TRIP, 1Y=nTRIP, 2A=RESET, 2Y=nRESET, 3A=GND, 4A=GND, 5A=GND, 6A=GND)74HC00(1A=nTRIP, 1B=ALQN, 1Y=ALARM, 2A=nRESET, 2B=ALARM, 2Y=ALQN, 3A=GND, 3B=GND, 4A=GND, 4B=GND)74HC02(1Y=READY, 1A=OPEN, 1B=ALARM, 2A=GND, 2B=GND, 3A=GND, 3B=GND, 4A=GND, 4B=GND)led(ALARM)led(READY)speaker{mode="buzz", tone=880}(ALARM)