ATmega DRAM Tester

• Supports 4164 and 41256 DRAM
• Uses standard March C- algorithm to fully test real-world DRAM faults
• Read mode for measuring row access time
• Only requires an Arduino Nano and a ZIF socket

Watch this video to learn about DRAM testing.

Using the tester

Disconnect power before inserting or removing chips for test.

In memory test mode (see Mode Select), the DRAM type is detected automatically. The full test takes 1.3 seconds for 4164 and 7.5 seconds for 41256. If no errors are detected, the green LED will be set and the chip can be considered working. The test repeats in a loop and can be left running to catch intermittent errors. If an error is detected, the red LED will persist until reset even if subsequent tests pass. The Arduino's built-in LED can also be observed flashing (2 long and 1 short per test) as it shares the same pin as the data line.

In access time measurement mode, an alternating pattern is written once and then read in a loop. If read errors are detected, the red LED will be set. The main purpose of the test is for triggering an oscilloscope from RAS (Arduino pin A4) and measuring the delay until Dout (Arduino pin D8) toggles.

In either mode, the ERR pin (Arduino pin A1) can be used for triggering a scope or logic analyzer at all points where an error is detected.

Assembling the circuit

Arduino Nano pinout

 Din-|PB5 |USB| PB4|-Green LED+
    -|    |___| PB3|-Red LED+
    -|          PB2|-Mode Select
    -|PC0       PB1|-A8
/ERR-|PC1       PB0|-Dout
 /RE-|PC2       PD7|-A7
 /WE-|PC3       PD6|-A6
/RAS-|PC4       PD5|-A5
/CAS-|PC5       PD4|-A4
    -|          PD3|-A3
    -|          PD2|-A2
  5V-|5V        GND|-GND
    -|             |-
 GND-|GND  ...  PD0|-A0
    -|     ...  PD1|-A1

/RE and /ERR aren't connected to DRAM, but provide test points for triggering a scope on read cycles and error conditions.

Mode Select

• SPST switch between Mode Select and GND
• Set open to select march C- test
• Set closed to select access time measurement

4164/41256 pinout

   A8-|1  \/ 16|-GND
  Din-|2     15|-CAS
   WE-|3     14|-Dout
  RAS-|4     13|-A6
   A0-|5     12|-A3
   A2-|6     11|-A4
   A1-|7     10|-A5
   5V-|8      9|-A7

Building the software

Use the PlatformIO plugin for VSCode.

Open the project folder with VSCode, select the environment for your board (nano, oldnano, uno), and click Upload.

See this video for help building with PlatformIO.

Distributed under the MIT license