Using MachXO2 as a SRAM device

Started by Piotr Wyderski May 25, 2021

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