ATmega1284 / ATmega1284P / ATmega644 / ATmega32 connection guide
ATmega1284 / ATmega1284P / ATmega644 / ATmega32 QFN-44 wiring guide with power, signal assignments, and bench checks.
Power and reset
RequiredUse a current-limited supply at a voltage permitted by the order code and system clock. Tie the listed supply pins to that rail. Fit one 100 nF ceramic capacitor close to each supply-and-ground pair. Use a 10 kΩ reset pull-up for this bench circuit.
- Target rail
- Ground
- Reset
Bench checks
- With power off, check for a short across the supply. Power on and measure voltage at every supply pin and at reset.
- Check the clock source configured by CKSEL. If a used part expects an external clock, provide it before attempting serial programming.
AN2519 §§2–3 and DS40002070B · Pin descriptions and clock source
Connection scenarios
Connect USART0 to a logic-level serial adapter
Use a UART adapter that supports the target’s I/O voltage. Cross the transmit and receive lines. Leave adapter power disconnected when using the bench supply.
Bench checks
- Configure both sides for the same baud rate, frame length, parity and stop bits. Base the MCU baud divider on the actual clock after prescaling.
- Send a known byte such as 0x55 from the MCU and check that it arrives unchanged. If it fails, inspect TX idle voltage and bit period before attaching the adapter TX line.
DS40002070B · USART0 asynchronous operation and pin assignments
QFN-44 wiring map
EP is the exposed center pad on the underside.
27 · AVCC
Analog supply. Connect it to the supply even if analog conversion is unused. Follow the data sheet’s filtering guidance for precision conversion.
Models and documents
Each package lists the documented order codes and variants covered by this map. Select the marked model to see its peripheral assignments and memory. Check the exact order code and datasheet revision before laying out a PCB.
- ATmega1284
- 128 KiB flash · 16 KiB SRAM · 4 KiB EEPROM. Choose the marked order code for voltage, clock, and temperature.
- ATmega1284-MU
- 128 KiB flash · 16 KiB SRAM · 4 KiB EEPROM · 1.8–5.5 V · 20 MHz maximum · -40 to +85 °C
- ATmega1284-MUR
- 128 KiB flash · 16 KiB SRAM · 4 KiB EEPROM · 1.8–5.5 V · 20 MHz maximum · -40 to +85 °C
- ATmega1284P
- 128 KiB flash · 16 KiB SRAM · 4 KiB EEPROM. Choose the marked order code for voltage, clock, and temperature.
- ATmega1284P-MU
- 128 KiB flash · 16 KiB SRAM · 4 KiB EEPROM · 1.8–5.5 V · 20 MHz maximum · -40 to +85 °C
- ATmega1284P-MUR
- 128 KiB flash · 16 KiB SRAM · 4 KiB EEPROM · 1.8–5.5 V · 20 MHz maximum · -40 to +85 °C
- ATmega644
- 64 KiB flash · 4 KiB SRAM · 2 KiB EEPROM. Choose the marked order code for voltage, clock, and temperature.
- ATmega644V-10MU
- 64 KiB flash · 4 KiB SRAM · 2 KiB EEPROM · 1.8–5.5 V · 10 MHz maximum · -40 to +85 °C
- ATmega644-20MU
- 64 KiB flash · 4 KiB SRAM · 2 KiB EEPROM · 2.7–5.5 V · 20 MHz maximum · -40 to +85 °C
- ATmega32
- 32 KiB flash · 2 KiB SRAM · 1 KiB EEPROM. Choose the marked order code for voltage, clock, and temperature.
- ATmega32L-8MU
- 32 KiB flash · 2 KiB SRAM · 1 KiB EEPROM · 2.7–5.5 V · 8 MHz maximum · -40 to +85 °C
- ATmega32L-8MUR
- 32 KiB flash · 2 KiB SRAM · 1 KiB EEPROM · 2.7–5.5 V · 8 MHz maximum · -40 to +85 °C
- ATmega32-16MU
- 32 KiB flash · 2 KiB SRAM · 1 KiB EEPROM · 4.5–5.5 V · 16 MHz maximum · -40 to +85 °C
- ATmega32-16MUR
- 32 KiB flash · 2 KiB SRAM · 1 KiB EEPROM · 4.5–5.5 V · 16 MHz maximum · -40 to +85 °C
- ATmega1284/ATmega1284P data sheet· DS40002070B · Pin configuration, electrical characteristics, ordering table and serial programming.
- ATmega644 data sheet· 2593O · Pin configuration, electrical characteristics, ordering table and serial programming.
- ATmega32 data sheet· 2503Q · Pin configuration, electrical characteristics, ordering table and serial programming.
- ATmega_DFP Device Family Pack· Machine-readable device definition: package contacts, peripheral routes, and memory sizes.
- AVR Microcontroller Hardware Design Considerations· Power supply, reset network, and programmer connection guidance.
- ATmega1284 documentation and errata· Check current manufacturer documentation, ordering status and silicon revision applicability.
- ATmega1284P documentation and errata· Check current manufacturer documentation, ordering status and silicon revision applicability.
- ATmega644 documentation and errata· Check current manufacturer documentation, ordering status and silicon revision applicability.
- ATmega32 documentation and errata· Check current manufacturer documentation, ordering status and silicon revision applicability.
- AVR source register· Source identifiers, applicability, retrieval dates, and SHA-256 digests.