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Contents

README

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ATMEGA644P-20PU

Microchip Tech · Microcontroller Units (MCUs/MPUs/SOCs) · DIP-40

ATMEGA644P-20PU from Microchip Tech, in a DIP-40. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin Name Type Function
1 PB0 bidirectional Port B bit 0, a bi-directional I/O pin with internal pull-up; alternate functions are XCK0, T0 and PCINT8.
2 PB1 bidirectional Port B bit 1, a bi-directional I/O pin with internal pull-up; alternate functions are T1, CLKO (divided system clock output) and PCINT9.
3 PB2 bidirectional Port B bit 2, a bi-directional I/O pin with internal pull-up; alternate functions are AIN0 (analog comparator positive input), INT2 and PCINT10.
4 PB3 bidirectional Port B bit 3, a bi-directional I/O pin with internal pull-up; alternate functions are AIN1 (analog comparator negative input), OC0A and PCINT11.
5 PB4 bidirectional Port B bit 4, a bi-directional I/O pin with internal pull-up; alternate functions are SS (SPI slave select), OC0B and PCINT12.
6 PB5 bidirectional Port B bit 5, a bi-directional I/O pin with internal pull-up; alternate functions are MOSI (SPI master output or slave input) and PCINT13.
7 PB6 bidirectional Port B bit 6, a bi-directional I/O pin with internal pull-up; alternate functions are MISO (SPI master input or slave output) and PCINT14.
8 PB7 bidirectional Port B bit 7, a bi-directional I/O pin with internal pull-up; alternate functions are SCK (SPI clock) and PCINT15.
9 RESET input Reset input; a low level longer than the minimum pulse length generates a reset, and shorter pulses are not guaranteed to do so.
10 VCC power_in Digital supply voltage.
11 GND power_in Ground.
12 XTAL2 output Output from the inverting Oscillator amplifier.
13 XTAL1 input Input to the inverting Oscillator amplifier and to the internal clock operating circuit.
14 PD0 bidirectional Port D bit 0, a bi-directional I/O pin with internal pull-up; alternate functions are RXD0 and PCINT24.
15 PD1 bidirectional Port D bit 1, a bi-directional I/O pin with internal pull-up; alternate functions are TXD0 and PCINT25.
16 PD2 bidirectional Port D bit 2, a bi-directional I/O pin with internal pull-up; alternate functions are INT0 and PCINT26.
17 PD3 bidirectional Port D bit 3, a bi-directional I/O pin with internal pull-up; alternate functions are INT1 and PCINT27.
18 PD4 bidirectional Port D bit 4, a bi-directional I/O pin with internal pull-up; alternate functions are OC1B and PCINT28.
19 PD5 bidirectional Port D bit 5, a bi-directional I/O pin with internal pull-up; alternate functions are OC1A and PCINT29.
20 PD6 bidirectional Port D bit 6, a bi-directional I/O pin with internal pull-up; alternate functions are OC2B, ICP and PCINT30.
21 PD7 bidirectional Port D bit 7, a bi-directional I/O pin with internal pull-up; alternate functions are OC2A and PCINT31.
22 PC0 bidirectional Port C bit 0, a bi-directional I/O pin with internal pull-up; alternate functions are SCL (two-wire serial clock) and PCINT16.
23 PC1 bidirectional Port C bit 1, a bi-directional I/O pin with internal pull-up; alternate functions are SDA (two-wire serial data) and PCINT17.
24 PC2 bidirectional Port C bit 2, a bi-directional I/O pin with internal pull-up; alternate functions are TCK (JTAG) and PCINT18.
25 PC3 bidirectional Port C bit 3, a bi-directional I/O pin with internal pull-up; alternate functions are TMS (JTAG) and PCINT19.
26 PC4 bidirectional Port C bit 4, a bi-directional I/O pin with internal pull-up; alternate functions are TDO (JTAG) and PCINT20.
27 PC5 bidirectional Port C bit 5, a bi-directional I/O pin with internal pull-up; alternate functions are TDI (JTAG) and PCINT21.
28 PC6 bidirectional Port C bit 6, a bi-directional I/O pin with internal pull-up; alternate functions are TOSC1 (Timer/Counter2 oscillator) and PCINT22.
29 PC7 bidirectional Port C bit 7, a bi-directional I/O pin with internal pull-up; alternate functions are TOSC2 (Timer/Counter2 oscillator) and PCINT23.
30 AVCC power_in Analog supply pin, shown in the pinout; the extracted text gives no further description.
31 GND power_in Ground.
32 AREF input Analog reference pin for the A/D converter, shown in the pinout; the extracted text gives no further description.
33 PA7 bidirectional Port A bit 7, serving as an ADC analog input and a bi-directional I/O pin with internal pull-up; alternate function is PCINT7.
34 PA6 bidirectional Port A bit 6, serving as an ADC analog input and a bi-directional I/O pin with internal pull-up; alternate function is PCINT6.
35 PA5 bidirectional Port A bit 5, serving as an ADC analog input and a bi-directional I/O pin with internal pull-up; alternate function is PCINT5.
36 PA4 bidirectional Port A bit 4, serving as an ADC analog input and a bi-directional I/O pin with internal pull-up; alternate function is PCINT4.
37 PA3 bidirectional Port A bit 3, serving as an ADC analog input and a bi-directional I/O pin with internal pull-up; alternate function is PCINT3.
38 PA2 bidirectional Port A bit 2, serving as an ADC analog input and a bi-directional I/O pin with internal pull-up; alternate function is PCINT2.
39 PA1 bidirectional Port A bit 1, serving as an ADC analog input and a bi-directional I/O pin with internal pull-up; alternate function is PCINT1.
40 PA0 bidirectional Port A bit 0, serving as an ADC analog input and a bi-directional I/O pin with internal pull-up; alternate function is PCINT0.

Key specifications

Parameter Value
Manufacturer Microchip Tech
Package DIP-40
Category Single Chip Microcomputer/Microcontroller
Pins 40

CAD (KiCad official)

  • Symbol: ATMEGA644P-20PU
  • Footprint: Package_DIP:DIP-40_W25.4mm
  • 3D model: DIP-40 (KiCad packages3D, STEP)
  • 3D model files: atmega644p-20pu-etched.step / atmega644p-20pu-etched.glb carry the MPN laser-etched on the die in a toggleable Adom.LaserEtch group (Fusion-ready); atmega644p-20pu.step / atmega644p-20pu.glb are the bare package body.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Microchip Tech datasheet (376 pp, sha256 198bacc71bec3b55, retrieved 2026-10-29, tier: manufacturer)
  • Extractor: parts-factory 2.0.0 / extract_pins 0.3, primary claude-haiku-5-5 (text), consensus claude-sonnet-5-5 (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF