Good afternoon.

No one tried to connect / use of DRAM computer? Nowhere did I find examples of schemes and information. I want to really understand a large memory connected to the microcontroller.

If you connect directly to difficult, is there any ready-made controllers DRAM? With a simple interface to use?

Hi Denis -

There are probably quite a few chips out there that provide SRAM or DRAM that you would access via an SPI or I2C serial connection (similar to the FLASH and EEPROM chips you can get).

These are not going to be very fast, since you are using a serial connection to move data back and forth one byte at a time. You also can't use it like the internal RAM - think of this more like a file on disk that you read and write to.

If what you are imagining is to add external RAM that would work just like the internal RAM, the problem with that is that the LPC1768 is a microcontroller, not a microprocessor. The important difference is that a microprocessor would have a data and address bus, which is how the chip would access the external memory quickly.

For example, there would be pins labled a0 though a15 for 16 bit addressing, and d0 through d15 for a 16-bit word size. One can see that this would add 32 more pins to the chip, thus making it more complex and expensive.

Sorry to go into lecture mode - not sure how familiar you are with these things (and of course people are welcome to argue with me :) - MCU vs. CPU is not really a black-and-white distinction any more).

Here's a couple examples of SPI or I2C serial-connected RAM:

NXP I2C SRAM

Microchip SPI SRAM

Hi Denis,

the LPC1768 is a Cortex M series device. The M stands for microcontroller and, as Dave said, they typically dont have support for external busses. The ARM Cortex A series (A for Application) generally support external memory. You will find the A8, A9 etc in many smartphones and tablets. Anyhow, depending on the required access speed and memorysize you might consider a SPI RAM or EEPROM device, possibly as SD memory card (very affordable upto several GB). You could also go for a USB stick (upto 64 GB) or even a USB harddisk.

Wim

Thank you for your answers. SRAM - does not fit, it has a very small size memory and is expensive. Serial interfaces - are not suitable because of their low speed. Ideal to be able to connect the memory of the laptop.