Configure NIOS firmware burning interface

Hi,

1) UART for burning/programing is the same as a common UART. when I use burning tools to send firmware(elf) via UART, the driver/bootloader in NIOS will get to know whether it is firmware or not, and will then save it at correct location in ROM/flash.

Yes, UART is just a standard serial interface — it doesn’t "know" the type of data. The ability to recognize firmware and write to flash comes from a bootloader that you must implement or include in your NIOS II system. By default, using nios2-download over UART loads the .elf to RAM, not Flash — it won’t persist after a reset.

To burn to flash via UART:

• You need a bootloader running on NIOS II that receives the data over UART and writes it to flash.

• Or use a prebuilt tool that supports flashing via UART (some vendors provide this).

Summary: UART works, but only if you have proper firmware on the device to handle the incoming data. It's not automatic.

2) I can use both UART or JTAG interface to burn both firmware(elf) and bitstream(sof).

JTAG can program:

FPGA bitstream (.sof)

NIOS II firmware (.elf)

UART can:

Transfer .elf into RAM (temporary execution only)

Not program .sof (bitstream) — this requires JTAG or a Flash device during power-up

Summary: You cannot program .sof via UART. Only firmware (and only if a bootloader is present).

3) I am using Quartus 18.1. In compilation report, I can see the total size of memory used, but I can't see the total memory available.

For ROM, I have the same question.

Quartus shows how much memory your design uses, but not how much is available directly in the report.

To find total available memory:

• Look up the FPGA part number in the Intel FPGA datasheet

• Example: Cyclone IV E EP4CE10 has 414 Kbits (~51.75 KB) of total embedded memory (M9Ks)

For ROM, if you use on-chip memory as ROM:

• Its size is defined when you add the memory block in Platform Designer (Qsys).

• Check Qsys or system.h file to see exact size.

4) in the following picture, Total PLL is 1. however, I didn't import PLL IP. why does it report 1 PLL used?

Valid and common question

Quartus sometimes inserts a PLL automatically even if you didn’t manually add one.

Reasons:

• Clock source needs frequency conversion to meet timing

• NIOS II debug interface or clock crossing domains

• IP blocks internally require it (e.g., clocked video or SDRAM controller)

Summary: It's normal. Quartus uses PLL resources behind the scenes even if you didn’t explicitly configure a PLL.