ATmega8A

{
  "schema_version": 1,
  "type": "component",
  "slug": "atmega8a",
  "title": "ATmega8A",
  "brief": "Microchip 8-bit AVR MCU, 28-pin DIP. 8 KB flash, 1 KB SRAM, 16 MHz, 23 I/O. The classic ATmega8. Datasheet-verified.",
  "version": "0.1.0",
  "license": "CC-BY-SA-4.0",
  "tags": [
    "component",
    "microcontroller",
    "mcu",
    "avr",
    "atmega",
    "pdip-28",
    "microchip"
  ],
  "component": {
    "mpn": "ATmega8A",
    "manufacturer": "Microchip Technology",
    "package": "PDIP-28",
    "pin_count": 28,
    "category": "Microcontroller",
    "subcategory": "8-bit AVR MCU",
    "datasheet": "https://ww1.microchip.com/downloads/en/DeviceDoc/ATmega8A-Data-Sheet-DS40001974B.pdf",
    "parts": {
      "symbol": "atmega8a.kicad_sym",
      "footprint": "atmega8a.kicad_mod",
      "model_3d": "atmega8a-etched.glb",
      "model_3d_plain": "atmega8a.glb",
      "lbr": "atmega8a.lbr",
      "model_3d_step": "atmega8a-etched.step",
      "model_3d_step_plain": "atmega8a.step"
    },
    "distributor_links": {},
    "pins": [
      {
        "number": "1",
        "name": "PC6/RESET",
        "type": "bidirectional",
        "description": "Port C bit 6, or active-low external Reset input. When the RSTDISBL fuse is programmed, PC6 acts as a general-purpose I/O; when unprogrammed (default), a low level longer than the minimum pulse length forces a chip reset even without a running clock."
      },
      {
        "number": "2",
        "name": "PD0/RXD",
        "type": "bidirectional",
        "description": "Port D bit 0. Alternate function is USART receive data input (RXD)."
      },
      {
        "number": "3",
        "name": "PD1/TXD",
        "type": "bidirectional",
        "description": "Port D bit 1. Alternate function is USART transmit data output (TXD)."
      },
      {
        "number": "4",
        "name": "PD2/INT0",
        "type": "bidirectional",
        "description": "Port D bit 2 with internal pull-up. Alternate function is external interrupt 0 (INT0)."
      },
      {
        "number": "5",
        "name": "PD3/INT1",
        "type": "bidirectional",
        "description": "Port D bit 3 with internal pull-up. Alternate function is external interrupt 1 (INT1)."
      },
      {
        "number": "6",
        "name": "PD4/XCK/T0",
        "type": "bidirectional",
        "description": "Port D bit 4. Alternate functions: USART external clock (XCK) and Timer/Counter0 external counter input (T0)."
      },
      {
        "number": "7",
        "name": "VCC",
        "type": "power_in",
        "description": "Digital supply voltage. Operating range 2.7-5.5 V. Decouple to GND with a 100 nF ceramic close to the pin."
      },
      {
        "number": "8",
        "name": "GND",
        "type": "power_in",
        "description": "Digital ground reference."
      },
      {
        "number": "9",
        "name": "PB6/XTAL1/TOSC1",
        "type": "bidirectional",
        "description": "Port B bit 6. Also serves as input to the inverting crystal oscillator amplifier (XTAL1) or Timer/Counter2 asynchronous oscillator input (TOSC1), depending on clock-source fuses and the AS2 bit in ASSR."
      },
      {
        "number": "10",
        "name": "PB7/XTAL2/TOSC2",
        "type": "bidirectional",
        "description": "Port B bit 7. Also serves as output of the inverting crystal oscillator amplifier (XTAL2) or Timer/Counter2 asynchronous oscillator output (TOSC2)."
      },
      {
        "number": "11",
        "name": "PD5/T1",
        "type": "bidirectional",
        "description": "Port D bit 5. Alternate function is Timer/Counter1 external counter input (T1)."
      },
      {
        "number": "12",
        "name": "PD6/AIN0",
        "type": "bidirectional",
        "description": "Port D bit 6. Alternate function is Analog Comparator positive input (AIN0)."
      },
      {
        "number": "13",
        "name": "PD7/AIN1",
        "type": "bidirectional",
        "description": "Port D bit 7. Alternate function is Analog Comparator negative input (AIN1)."
      },
      {
        "number": "14",
        "name": "PB0/ICP1",
        "type": "bidirectional",
        "description": "Port B bit 0. Alternate function is Timer/Counter1 input capture pin (ICP1)."
      },
      {
        "number": "15",
        "name": "PB1/OC1A",
        "type": "bidirectional",
        "description": "Port B bit 1. Alternate function is Timer/Counter1 output compare match A (OC1A) - PWM output."
      },
      {
        "number": "16",
        "name": "PB2/SS/OC1B",
        "type": "bidirectional",
        "description": "Port B bit 2. Alternate functions: SPI slave-select (SS, active low) and Timer/Counter1 output compare match B (OC1B)."
      },
      {
        "number": "17",
        "name": "PB3/MOSI/OC2",
        "type": "bidirectional",
        "description": "Port B bit 3. Alternate functions: SPI Master Out Slave In (MOSI) and Timer/Counter2 output compare match (OC2). Also serves as MOSI during SPI serial programming."
      },
      {
        "number": "18",
        "name": "PB4/MISO",
        "type": "bidirectional",
        "description": "Port B bit 4. Alternate function is SPI Master In Slave Out (MISO). Also serves as MISO during SPI serial programming."
      },
      {
        "number": "19",
        "name": "PB5/SCK",
        "type": "bidirectional",
        "description": "Port B bit 5. Alternate function is SPI serial clock (SCK). Also serves as SCK during SPI serial programming."
      },
      {
        "number": "20",
        "name": "AVCC",
        "type": "power_in",
        "description": "Analog supply pin for the A/D converter, Port C (3:0), and (on TQFP/VQFN) ADC7:6. Must be externally connected to VCC even if the ADC is unused; if the ADC is used, tie to VCC through a low-pass filter (e.g. 10 uH + 100 nF)."
      },
      {
        "number": "21",
        "name": "AREF",
        "type": "passive",
        "description": "Analog reference input for the A/D converter. Bypass to AGND with a ~100 nF capacitor when using the external reference; leave for internal reference selection via ADMUX (REFS1:0)."
      },
      {
        "number": "22",
        "name": "GND",
        "type": "power_in",
        "description": "Analog/second ground reference. Tie to the same ground plane as pin 8."
      },
      {
        "number": "23",
        "name": "PC0/ADC0",
        "type": "bidirectional",
        "description": "Port C bit 0. Alternate function is ADC channel 0 input (10-bit)."
      },
      {
        "number": "24",
        "name": "PC1/ADC1",
        "type": "bidirectional",
        "description": "Port C bit 1. Alternate function is ADC channel 1 input (10-bit)."
      },
      {
        "number": "25",
        "name": "PC2/ADC2",
        "type": "bidirectional",
        "description": "Port C bit 2. Alternate function is ADC channel 2 input (10-bit)."
      },
      {
        "number": "26",
        "name": "PC3/ADC3",
        "type": "bidirectional",
        "description": "Port C bit 3. Alternate function is ADC channel 3 input (10-bit)."
      },
      {
        "number": "27",
        "name": "PC4/ADC4/SDA",
        "type": "bidirectional",
        "description": "Port C bit 4. Alternate functions: ADC channel 4 input and Two-wire Serial Interface (I2C) data line SDA (open-drain when TWI enabled via TWCR)."
      },
      {
        "number": "28",
        "name": "PC5/ADC5/SCL",
        "type": "bidirectional",
        "description": "Port C bit 5. Alternate functions: ADC channel 5 input and Two-wire Serial Interface (I2C) clock line SCL (open-drain when TWI enabled via TWCR)."
      }
    ],
    "provenance": {
      "extractor": "ds2sf",
      "datasheet": {
        "url": "https://ww1.microchip.com/downloads/en/DeviceDoc/ATmega8A-Data-Sheet-DS40001974B.pdf",
        "pages": 14,
        "sha256": "7219f52fb53d9a46",
        "source_tier": "mfr"
      },
      "cad": "KiCad official (CC-BY-SA 4.0)",
      "pins": {
        "total": 28,
        "described": 28,
        "cites_pages": true,
        "refuses_to_fabricate": true
      }
    },
    "viewers": {
      "symbol": "viewers/symbol.html",
      "footprint": "viewers/footprint.html"
    },
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        "role": "plain",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
        "seat": "body on z = 0, through-hole leads below",
        "extents_mm": [
          7.874,
          35.56,
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        "zmin_mm": -3.3,
        "centre_offset_mm": 0.0,
        "footprint_binding": "identity",
        "sha256": "7bf4503e368ad9b7a3eddfa94bc8dee656da5d6921b677e17307b3d7f29177ab",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      },
      {
        "file": "atmega8a-etched.step",
        "role": "eda",
        "up": "Z",
        "units": "mm",
        "origin": "footprint origin = pad-pattern centre",
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        "zmin_mm": -3.3,
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        "footprint_binding": "identity",
        "sha256": "2ce076c9bc2b078ac614ed55be067638728a17a8e64f7d838f1acc9faa647f09",
        "checked": "2026-10-07",
        "checked_by": "factory/step_pose.py (Z-up, origin, seat, binding)"
      }
    ]
  },
  "metadata": {
    "specs": {
      "Core": "8-bit AVR RISC",
      "Flash": "8 KB",
      "SRAM": "1 KB",
      "EEPROM": "512 B",
      "Max clock": "16 MHz",
      "GPIO": "23 (ports B/C/D)",
      "ADC": "6-channel 10-bit",
      "Serial": "USART + SPI + I2C (TWI)",
      "Supply voltage": "2.7-5.5 V",
      "Package": "PDIP-28"
    }
  },
  "sections": [
    "hero",
    "viewers",
    "readme",
    "breadcrumbs",
    "info"
  ],
  "discovery_triggers": [
    "atmega8a",
    "atmega8",
    "8-bit avr",
    "classic avr mcu",
    "atmega8 dip"
  ],
  "discovery_pitch": "ATmega8A 8-bit AVR microcontroller (28-pin DIP) with datasheet-verified pinout, KiCad symbol/footprint/3D, and full provenance.",
  "author": {
    "name": "Ray",
    "email": "[email protected]"
  },
  "dependencies": {},
  "hero": {
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    "path": "docs/hero.png"
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    "atmega8a.lbr",
    "docs/hero.png",
    "docs/atmega8a-datasheet.pdf",
    "viewers/symbol.html",
    "viewers/footprint.html",
    "atmega8a-etched.step"
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}