Lesson 4. The CD4511B decoder

After this lesson the library has the CD4511B — it turns a binary code into a digit on a 7-segment display. The CD4029 counts, the CD4511 shows.

4.1. Idea: seven strokes

A digit on the display is seven segments a–g. Each digit lights its own set: 1 — b c, 8 — all seven. A decoder is a table: the code D C B A at the input, seven wires at the output.

4.2. Idea: latch, blanking, lamp test

• LE = 0 — the code goes straight through; LE = 1 — the CD4511 holds the last digit (a latch on TG switches);
• BL = 0 — the display is blank;
• LT = 0 — all segments light up: a check that none is burnt out.

In this kit LT, BL are at 1 and LE at 0: we just show the number.

4.3. Idea: a switch on two transistors

TG is an nmos and a pmos in parallel. One passes 0 well, the other passes 1; together — any signal. The gates always get opposite signals: N = 1 and P = 0 — closed.

4.4. Build

The same project. The library needs the lesson 0 gates, NOR3, NOR4 and CD4029 (lesson 3).

Step 1. Chip TG — a switch on a pair of transistors

As on the TI drawings: nmos and pmos in parallel between A and B. N = 1 and P = 0 — the switch is closed, N = 0 and P = 1 — open. The gates always get opposite signals.

Ctrl+G → name TG. Legs: inputs A, N, P; outputs B.

Step 2. Chip CD4511 — BCD → 7-segment decoder with a latch

Package pins from the TI datasheet: 1 B, 2 C, 3 LT, 4 BL, 5 LE, 6 D, 7 A, 9 e, 10 d, 11 c, 12 b, 13 a, 14 g, 15 f; 8 — VSS, 16 — VDD. Inside — TI Fig. 8: latches on TG (LE = 0 — transparent, LE = 1 — holds), a decoder on NOR3/NOR4, blanking BL = 0 (all segments off), lamp test LT = 0 (all lit), NOT drivers at the output. Codes 10–15 — blank.

Ctrl+G → name CD4511. Legs: inputs B, C, LT, BL, LE, D, A; outputs e, d, c, b, a, g, f.

Step 3. CD4029 counter, switch, generator, button

Clock — 1Hz. Reset — RST. The CD4029 counts in decade (BD = 0); Reset goes to PE: while the button is pressed the counter loads J = 0000. Free inputs — to GND.

Step 4. The CD4511 decoder

Step 5. Display

1. Place a Segment LCD (the palette, the display icon next to the dot display).
2. ⚙ → the Size field: 24 × 30 (click the number, type, Enter).
3. The right panel Stamps → size L 21 → section Digits → the first tile (an eight without a point) → click the centre of the field → Esc.
4. S (select) → click the top segment → Enter (New pin) → name a → Enter. The same clockwise: top right b, bottom right c, bottom d, bottom left e, top left f, middle g.
5. Close the editor: the body has seven legs a–g. Labels on the legs:

4.5. Check

1. Clock — 1Hz. Press Reset — the display shows 0.
2. UD = 1: 0, 1, 2 … 9, 0 — the digit changes on every clock.
3. UD = 0: counting down — 0, 9, 8 …

After the check delete the probe — TG, CD4511 stay in the library. Keep the display (without labels): lesson 6 copies it.

Lesson 4 paste (Cmd+I)

You need the lesson 0 gates, NOR3, NOR4 and CD4029 (lesson 3). The paste does not place the display — place it by hand ("Display" step): after the stamp the segments are named S1…S7, you give them the names a–g.

# Lesson 4 — CD4511B: a BCD to 7-segment decoder with a latch (TI Fig. 8); CD4029 counter → CD4511 → a digit.# Paste: Cmd+I into the same project (lesson 0 gates, NOR3, NOR4 and CD4029 from lesson 3 needed). chip TG {  portIn(A)  portIn(N)  portIn(P)  portOut(B)  nmos(N, A, B)  pmos(P, A, B)} chip CD4511 {  portIn(B)  portIn(C)  portIn(LT)  portIn(BL)  portIn(LE)  portIn(D)  portIn(A)  portOut(e)  portOut(d)  portOut(c)  portOut(b)  portOut(a)  portOut(g)  portOut(f)  NOT(A, n1)  NOT(B, n2)  NOT(C, n3)  NOT(D, n4)  NOT(LE, n5)  TG(A=n1, N=n5, P=n6, B=n7)  TG(A=n2, N=n5, P=n6, B=n8)  TG(A=n3, N=n5, P=n6, B=n9)  TG(A=n4, N=n5, P=n6, B=n10)  NOT(n5, n6)  TG(A=n11, N=n6, P=n5, B=n7)  NOT(n7, n12)  NOT(n12, n11)  TG(A=n13, N=n6, P=n5, B=n8)  NOT(n8, n14)  NOT(n14, n13)  TG(A=n15, N=n6, P=n5, B=n9)  NOT(n9, n16)  NOT(n16, n15)  TG(A=n17, N=n6, P=n5, B=n10)  NOT(n10, n18)  NOT(n18, n17)  NOR3(A=n11, B=n13, C=n15, Y=n19)  NOR(n13, n16, n20)  NOR3(A=n15, B=n13, C=n12, Y=n21)  NOR3(A=n11, B=n14, C=n15, Y=n22)  NOR3(A=n12, B=n14, C=n15, Y=n23)  NOR3(A=n12, B=n13, C=n16, Y=n24)  NOR3(A=n11, B=n14, C=n16, Y=n25)  NAND(n15, n13, n26)  NAND(n26, n18, n27)  NOR4(A=n11, B=n14, C=n16, D=n18, Y=n28)  NOR4(A=n12, B=n14, C=n16, D=n18, Y=n29)  NAND(BL, n27, n30)  NOR4(A=n30, B=n23, C=n21, D=n28, Y=n31)  NOR3(A=n30, B=n22, C=n21, Y=n32)  NOR(n30, n24, n33)  NOR4(A=n30, B=n23, C=n19, D=n25, Y=n34)  NOR3(A=n30, B=n12, C=n23, Y=n35)  NOR4(A=n30, B=n28, C=n20, D=n19, Y=n36)  NOR4(A=n30, B=n19, C=n28, D=n29, Y=n37)  NOR(n31, n38, n39)  NOR(n32, n38, n40)  NOR(n33, n38, n41)  NOR(n34, n38, n42)  NOR(n35, n38, n43)  NOR(n36, n38, n44)  NOR(n37, n38, n45)  NOT(LT, n38)  NOT(n39, a)  NOT(n40, b)  NOT(n41, c)  NOT(n42, d)  NOT(n43, e)  NOT(n44, f)  NOT(n45, g)} power(VCC)ground(GND)input(UD)clock(CLOCK)button{label="Reset"}(RST)CD4029(PE=RST, Q4=U3, J4=GND, J1=GND, CI=GND, Q1=U0, BD=GND, UD=UD, Q2=U1, J2=GND, J3=GND, Q3=U2, CLOCK=CLOCK)CD4511(B=U1, C=U2, LT=VCC, BL=VCC, LE=GND, D=U3, A=U0, e=Ue, d=Ud, c=Uc, b=Ub, a=Ua, g=Ug, f=Uf)