Spark Logic

Atmel AT89C52 connection guide

Atmel AT89C52 PLCC-44 wiring guide with power, signal assignments, and bench checks.

PDIP-40 40 contacts

PLCC-44

44 contacts Current package
TQFP-44 44 contacts
PQFP-44 44 contacts

Atmel · 44J, J-shaped leads at 1.27 mm pitch. Ordering suffix J.

Power and internal code selection

Required

Power VCC from a regulated 5 V supply (±5% for these examples). Place a 100 nF ceramic bypass between VCC and GND. The high strap on EA selects the installed Flash at reset address 0000h.

100 nF between VCC rail and GroundVCC rail100 nFGround

Bench checks

  • Confirm the package pin 1 mark before applying power and measure VCC relative to ground at the IC.
  • Use a 100 nF X7R capacitor rated at least 16 V as the local high-frequency bypass. Keep its loop short.
  • Confirm the on-chip Flash contains the intended startup code before selecting internal execution.

Atmel AT89C52, 0313H–02/00, pp. 4, 17, 22

Connection scenarios

Measure the Timer 2 clock output

Use P1.0/T2 as a programmable clock output. Observe it with a high-impedance scope probe and a short ground connection.

Bench checks

  • Leave the P1.0 port latch at 1. Stop Timer 2, set T2MOD = 02h, load RCAP2H:RCAP2L and TH2:TL2 with FF00h, then write T2CON = 04h to start the timer.
  • At 11.0592 MHz, expect a 50% duty cycle at 10.8 kHz nominal. The divisor is 4 × (65536 − FF00h) = 1024.
  • Use Timer 1 for independently chosen UART baud rates. Timer 2 clock output and Timer 2 baud generation share the reload value.

Atmel AT89C52, 0313H–02/00, pp. 8, 10–11, Figure 5

PLCC-44 wiring map

Highlighted contacts are used in the required step or selected circuit. Select a contact to inspect it.

PLCC-44
Top view, index chamfer at upper left. Pin 1 is centered on the top edge. Scroll the map to reach all contacts.
Selected pin details

44 · VCC

Supply · Power

Connect to the regulated positive supply. Place the bypass capacitor close to VCC and ground.

Atmel 0313H–02/00, pp. 1, 3–5

Electrical limits · Pin in the reference

Models and documents

This reference resolves the abbreviated 89C52 name to Atmel’s AT89C52, document 0313H. It covers all four package drawings and the listed 12/16/20/24 MHz speed grades. Check the full marking on parts from other manufacturers. The AT89S52 uses its own programming interface and datasheet.

AT89C52-12
Up to 12 MHz, 4.0–6.0 V. AT89C52-12JC: 0–70 °C. AT89C52-12JI: −40–85 °C. 8 KiB Flash and 256 B RAM.
AT89C52-16
Up to 16 MHz, 4.0–6.0 V. AT89C52-16JC: 0–70 °C. AT89C52-16JI: −40–85 °C. 8 KiB Flash and 256 B RAM.
AT89C52-20
Up to 20 MHz, 4.0–6.0 V. AT89C52-20JC: 0–70 °C. AT89C52-20JI: −40–85 °C. 8 KiB Flash and 256 B RAM.
AT89C52-24
Up to 24 MHz, 4.0–6.0 V. AT89C52-24JC: 0–70 °C. AT89C52-24JI: −40–85 °C. 8 KiB Flash and 256 B RAM.
  • Datasheet for AT89C52· Atmel 0313H–02/00, February 2000. Pin configurations p. 1, pin descriptions pp. 3–4, SFR reset p. 5, Timer 2 pp. 6–10, oscillator p. 12, DC p. 17, clock drive p. 20, ordering and package drawings pp. 22–23. SHA-256 f8d392b5cc25322766180e74d323b5c8abd647c98f9d4fbfc6f99a7d1f89e4bd.
  • Intel MCS-51 Family User’s Manual· Intel 272383-002, February 1994, chapter 3. Core operation, port latches and serial interface. The AT89C52 datasheet governs its own electrical limits and Timer 2 extensions.