commit	454aadbbbb21f30725c2b09d751eaf7610d4a97c	[log] [tgz]
author	Kesami Hagiwara <kesami.hagiwara@swhwc.com>	Wed Sep 07 23:49:14 2022 +0900
committer	Kesami Hagiwara <kesami.hagiwara@swhwc.com>	Wed Sep 07 23:49:14 2022 +0900
tree	970b47019a49138a5c17d70bd54fe6d3648d9893
parent	08831125a1beb1f1a8a7bd6f705334ae7394bda3 [diff]

tree: 970b47019a49138a5c17d70bd54fe6d3648d9893

README.md

Marmot RISC-V SoC

A Customizable RISC-V Microcomputer

A custom microcomputer design is useful when off-the-shelf general-purpose microcontrollers fail to meet the system needs. The rocket SoC generator automatically generate an SoC. It circumvents labor-intensive, error-prone, top-level SoC design.

SoC Customization Flow

The Rocket SoC Generator and Caravel SoC Template are reused to create a twin (not identical) RISC-V SoC consisting of one Rocket RISC-V and one Caravel RISC-V. The objectives here is to save hours on design verification and reduce power consumption rather than saving die area or chip cost.

graph TD
A(A SoC Wish List) -- SoC Description in Chisel--> B
B[The Rocket SoC Generator] --SoC RTL--> D[The OpenLane Flow]
C[Caravel SoC Harness] --Harness RTL--> D
B --FPGA RTL--> L
P[RISC-V IDE Tools]--Code and Executables-->H
L[_Yosys_+nextpnr] --Bitstream--> K[Lattice ECP5 Eval Board]
E(Caravel Firmware)  --Init, Monitoring, Debug--> C
D --Sky130 GDS II Layout Data--> F[eFabless MPW]
O[Xschema]--Circuit schematics-->J
F --MPW Chips--> H
F --MPW Chips--> I
I[Caravel EVB] --Breadboarding-->H{User system}
J[KiCad]--Gerber and BOM-->H

Implementing low power operations

The following shows a scheme to manage clock, reset, power and low power state.

sequenceDiagram
Note right of System: Powers<br/>Caravel<br/>Chip.
System -->> Harness: Reset
System -->> Harness: Reset
System -->> Caravel SoC: Reset
Harness -->> Caravel SoC: core clock
Harness -->> Caravel SoC: core reset
Caravel SoC->>Harness: Configuration of clk, DLL
Caravel SoC->>Harness: Configure pad data routing and GPIO
Harness-->>Rocket SoC: Set user_clock full speed
Caravel SoC->>Rocket SoC: Reset user logic
Note left of Rocket SoC: Rocket boots<br/>from ROM logic<br/>XIP SPI flash<br/>runs on DTIM.
Rocket SoC -->> Caravel SoC: Rocket is running OK
Note left of Caravel SoC: Acknoleging <br/>Rocket OK<br/>tuns off External<br/>CPG power<br/>via GPIO or I2C.
Caravel SoC->>System: Turn off External CPG Power
Note left of Rocket SoC: Rocket sends message<br/>"Bring Caravel<br/>to lowest power state"<br/>e.g. wishbone mailbox<br/>and interrupt.
Rocket SoC->>Caravel SoC: "Go low on power"
Note left of Caravel SoC: Management SoC sets<br/>Clocking and DLL<br/> to Caravel's<br/>lowest power state<br/>via System control.
Caravel SoC->> Harness: Caravel goes low power.
Note left of Rocket SoC: Rocket gets<br/>wake up signal<br/>from RTC.
Rocket SoC->>Caravel SoC: "Go full power"
Caravel SoC->>Harness: Configure Clock, DLL via System control
Caravel SoC->>Rocket SoC: "Went full power".

Features

Unit	Description
RISC-V CPU	RV32IMAC, M/S/U-mode (Rocket)
I-Cache	Instruction cache: 16 KiB (Up to 8 KiB can be configured as Instruction Tightly Integrated Memory (ITIM))
D-Cache	Data cache: 8 KiB
QSPI0	Quad Serial Peripheral Interface (QSPI) for (Q)SPI-Flash memory (XIP supported)
QSPI1	Quad Serial Peripheral Interface (QSPI) for (Q)SPI-Peripherals (CS x2)
QSPI2	Quad Serial Peripheral Interface (QSPI) for (Q)SPI-PSRAM (XIP supported)
UART0-4	Universal Asynchronous Receiver/Transmitter (UART) x5
I2C0-1	Inter-Integrated Circuit (I2C) Master Interface x2
PWM0-2	Pulse Width Modulator (PWM) (4x 16-bit comparators/unit) x3
Debug	Debug functions, JTAG I/F

Refer to Freedom E310-G002 Manual for detailed specification of each unit except QSPI2. For QSPI2, refer to docs/SPI_with_PSRAM_Interface.pdf .

Pinouts

mprj_io[#]	Mgmt. SoC	Marmot IOF0	Marmot IOF1	Marmot GPIO
0	JTAG	-	-	-
1	SDO	TDO	-	-
2	SDI	TDI	-	-
3	CSB	TMS	-	-
4	SCK	TCK	-	-
5	ser_rx	UART0_rx	-	-
6	ser_tx	UART0_tx	-	-
7	irq	QSPI1_csb[1]	-	GPIO[24]
8	flash2_csb	QSPI0_flash_csb	-	-
9	flash2_sck	QSPI0_flash_sck	-	-
10	flash2_io[0]	QSPI0_flash_io[0]	-	-
11	flash2_io[1]	QSPI0_flash_io[1]	-	-
12	-	QSPI0_flash_io[2]	-	-
13	-	QSPI0_flash_io[3]	-	-
14	-	QSPI1_csb[0]	-	GPIO[0]
15	-	QSPI1_sck	-	GPIO[1]
16	-	QSPI1_io[0]	-	GPIO[2]
17	-	QSPI1_io[1]	-	GPIO[3]
18	-	QSPI1_io[2]	-	GPIO[4]
19	-	QSPI1_io[3]	-	GPIO[5]
20	-	QSPI2_csb	-	-
21	-	QSPI2_sck	-	-
22	-	QSPI2_io[0]	-	-
23	-	QSPI2_io[1]	-	-
24	-	QSPI2_io[2]	-	-
25	-	QSPI2_io[3]	-	-
26	-	I2C0_sda	PWM0_0	GPIO[12]
27	-	I2C0_scl	PWM0_1	GPIO[13]
28	-	I2C1_sda	PWM0_2	GPIO[14]
29	-	I2C1_scl	PWM0_3	GPIO[15]
30	-	UART1_rx	PWM1_0	GPIO[16]
31	-	UART1_tx	PWM1_1	GPIO[17]
32	-	UART2_rx	PWM1_2	GPIO[18]
33	-	UART2_tx	PWM1_3	GPIO[19]
34	-	UART3_rx	PWM2_0	GPIO[20]
35	-	UART3_tx	PWM2_1	GPIO[21]
36	-	UART4_rx	PWM2_2	GPIO[22]
37	-	UART4_tx	PWM2_3	GPIO[23]

Address Map

Base	Top	Attribute	Unit	Description
0x0000_0000	0x0000_0FFF	RWX A	Debug	Debug Address Space
0x0000_1000	0x0000_2FFF	-	Reserved	-
0x0000_3000	0x0000_3FFF	RWX A	Error Device	Error Address Space
0x0000_4000	0x0000_FFFF	-	Reserved	-
0x0001_0000	0x0001_1FFF	R XC	Boot ROM	Boot ROM (8 KiB)
0x0001_2000	0x0002_1FFF	-	Reserved	-
0x0200_0000	0x0200_FFFF	RW A	CLINT	Core-Local Interruptor
0x0201_0000	0x07FF_FFFF	-	Reserved	-
0x0800_0000	0x0800_1FFF	RWX A	ITIM	Instruction Tightly Integrated Memory (up to 8KiB)
0x0800_2000	0x0BFF_FFFF	-	Reserved	-
0x0C00_0000	0x0FFF_FFFF	RW A	PLIC	Platform-Level Interrupt Controller
0x1000_0000	0x1000_0FFF	RW A	AON	Always-On Domain (WDT, RTC, PMU, etc.)
0x1000_1000	0x1001_1FFF	-	Reserved	-
0x1001_2000	0x1001_2FFF	RW A	GPlO	General Purpose Input/Output Controller
0x1001_3000	0x1001_3FFF	RW A	UART0	Universal Asynchronous Receiver/ Transmitter #0
0x1001_4000	0x1001_4FFF	RW A	QSPI0	Quad Serial Peripheral Interface #0 for (Q)SPI-Flash memory (XIP supported)
0x1001_5000	0x1001_5FFF	RW A	PWM0	Pulse Width Modulator #0
0x1001_6000	0x1001_6FFF	RW A	I2C0	Inter-Integrated Circuit Master Interface #0
0x1001_7000	0x1002_2FFF	-	Reserved	-
0x1002_3000	0x1002_3FFF	RW A	UART1	Universal Asynchronous Receiver/ Transmitter #1
0x1002_4000	0x1002_4FFF	RW A	QSPI1	Quad Serial Peripheral Interface #1 for (Q)SPI-Peripherals
0x1002_5000	0x1002_5FFF	RW A	PWM1	Pulse Width Modulator #1
0x1002_6000	0x1002_6FFF	RW A	I2C1	Inter-Integrated Circuit Master Interface #1
0x1002_7000	0x1003_2FFF	-	Reserved	-
0x1003_3000	0x1003_3FFF	RW A	UART2	Universal Asynchronous Receiver/ Transmitter #2
0x1003_4000	0x1003_4FFF	RW A	QSPI2	Quad Serial Peripheral Interface #2 for (Q)SPI-PSRAM (XIP supported)
0x1003_5000	0x1FFF_FFFF	RW A	PWM2	Pulse Width Modulator #2
0x1004_3000	0x1005_2FFF	RW A	UART3	Universal Asynchronous Receiver/ Transmitter #3
0x1004_4000	0x1005_2FFF	-	Reserved	-
0x1005_3000	0x1005_3FFF	RW A	UART4	Universal Asynchronous Receiver/ Transmitter #4
0x1005_4000	0x1FFF_FFFF	-	Reserved	-
0x2000_0000	0x3FFF_FFFF	R XC	(Q)SPI-Flash	Off-Chip (Q)SPI-Flash Memory (up to 512 MiB)
0x4000_0000	0x5FFF_FFFF	RWXC	(Q)SPI-PSRAM	Off-Chip (Q)SPI-PSRAM (up to 512 MiB)
0x6000_0000	0xFFFF_FFFF	-	Reserved	-

Reference

Marmot RISC-V ASIC for Motor Control (Efabless MPW-7 project)

Freedom E310-G002 Manual

Chipyard Framework

The Rocket Chip Generator

Efabless Caravel Architecture

Acknowledgements

This work is based on results obtained from project, JPNP16007, commissioned by The New Energy and Industrial Technology Development Organization (NEDO).