We are going to start our breadboard RISC-V project. We build a simple RISC-V with students to fulfill the below requirements. The breadboard CPU is simple, but we will be in full stack, code the testing program in GCC, debug via GDB with our own jtag and by openocd.

Requirements:

1. A controllable program counter. We can set its speed and pause it at any time manually
2. Support some basic instructions such as below
3. Provide LED to indicate the status and register values on board
4. Data bus & instruction bus
5. 3 Stage pipeline and visualize it
6. We use STM32 to build the USB tag and plug to our breadboard RISC-V, write openocd driver and able to dump out registers and single step via GDB

Remark 1:

Outside the RISC-V we still need some components such as a programmable clock generator, we do all that by ATtiny85 and flash it via this device

Remark 2:

For the memory rather than using gates, we use dip memory such as 24AA32AF and this device and flash the EEPROM memory

Bill Of Material

	Thing	Qty	Price
	Digital Design and Computer Architecture: RISC-V Edition	4	$350
	Breadboard	60	$180
	We need some OLED (don’t know how many, just buy them all) 0.96 inch x 20 + 1.3 inch x 20	40	$600
	LED	200	$80
	8-segments LED	100	$300
	USB Power Supply	3	$60
	Button x 50 for each student	3	$80
	Cable x 300 for each student	3	$50
	We need some gates but I don’t know which one, so buy them all	3	$800
	Switch	3	$80
	STM32 board and JTag to offload some logic outside RISC-V	3	$100
	Tester	3	$300
	Logic Analyzer	3	$80
	Ben Eater Complete 8-bit breadboard computer kit bundle	3	$7020
	Multimeter	3	$800
		Total =	$10880

2023-04-23 by admin