Summary of Interfacing DRAM Memory using AVR microcontroller
Jesperh demonstrated that an AVR microcontroller (Atmel AT90S8515/ATmega8515 family) can interface with DRAM by implementing RAS/CAS control and refresh routines in software. He connected a Hitachi M5M44800 512k×8 DRAM to the microcontroller, programmed in C, and achieved low power operation (2–3 mA during refresh/low access). The DRAM vastly expands memory compared to the MCU’s 512-byte internal RAM.
Parts used in the DRAM with AVR project:
- Atmel AT90S8515 (ATmega8515) microcontroller
- Hitachi M5M44800 512k×8 DRAM chip
- Address buss wiring (microcontroller to DRAM address pins)
- Data buss wiring (microcontroller to DRAM data pins)
- Control signal wiring for RAS and CAS
- Power supply (suitable Vcc for MCU and DRAM)
- Decoupling capacitors for power stability
- Optional level shifting or buffering (if required)
- Development tools for C programming (compiler and programmer)
Is it possible to use DRAM with microcontroller AVR? Yes, it is possible. Jesperh has proved it. He hooked up a DRAM to a small processor (in this case an Microcontroller Atmel 8515), and handle the RAS/CAS sequencing and refresh in software.
The type of DRAM is Hitatchi M5M44800, a 512k*8 DRAM!. Bigger than the original memory of microcontroller AT90S8515 that is 512 byte RAM. The project use C to programm it. The chip required small power consumption, only takes about 2-3 mA when just refreshing and with a low access rate.
For more detail: Interfacing DRAM Memory using AVR microcontroller
- Is it possible to use DRAM with an AVR microcontroller?
Yes, Jesperh proved it by interfacing a Hitachi M5M44800 DRAM to an AT90S8515 and handling control in software. - Which DRAM was used in the project?
The Hitachi M5M44800 512k×8 DRAM was used. - Which microcontroller was used to interface the DRAM?
An Atmel AT90S8515 (ATmega8515 family) microcontroller was used. - How are RAS and CAS handled in this project?
RAS and CAS sequencing and refresh are handled in software by the microcontroller. - What programming language was used for the project?
The project was programmed in C. - How much power does the DRAM consume during refresh or low access?
The DRAM consumes about 2–3 mA when just refreshing and with a low access rate. - How does the DRAM compare to the microcontroller's internal RAM?
The DRAM (512k×8) is much larger than the microcontroller's internal 512-byte RAM.
