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devel / comp.arch.fpga / Using MachXO2 as a SRAM device

o Using MachXO2 as a SRAM devicePiotr Wyderski

Using MachXO2 as a SRAM device


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From: (Piotr Wyderski)
Newsgroups: comp.arch.fpga
Subject: Using MachXO2 as a SRAM device
Date: Tue, 25 May 2021 19:19:02 +0200
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 by: Piotr Wyderski - Tue, 25 May 2021 17:19 UTC


I have an application where replacing the configuration of the FPGA will
occur frequently and hence I do not want to use the built-in FLASH.
Having an always-blank device on the board is perfectly fine. The
MachXO2 chip is ideal for many reasons, so I don't want to replace it
with a purely SRAM-based FPGA.

Now, the "MachXO2 Programming and Configuration Usage Guide" says the
FLASH can be programmed via I2C, SPI and JTAG, but the SRAM only via the
JTAG. Thy will be done, the JTAG stream will be bit-banged by an MCU.
But how do I program the SRAM? The document is very detailed when it
comes to *programming*, but I can't see much about (re)configuration.
E.g. on page 59 there is a list of programming commands, say,
LSC_PROG_INCR_NV -- "Program one Flash page. Can be used to program the
Configuration Flash, or UFM." How about the SRAM? The documentation
asserts it can be done, but does not care to explain how. I assume it
must be simple, but I am obviously missing something. Could you please help?

Best regards, Piotr

devel / comp.arch.fpga / Using MachXO2 as a SRAM device


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