Datasheet
Table Of Contents
- RP2040 Datasheet
- Colophon
- Chapter 1. Introduction
- Chapter 2. System Description
- 2.1. Bus Fabric
- 2.2. Address Map
- 2.3. Processor subsystem
- 2.4. Cortex-M0+
- 2.5. DMA
- 2.6. Memory
- 2.7. Boot Sequence
- 2.8. Bootrom
- 2.9. Power Supplies
- 2.10. Core Supply Regulator
- 2.11. Power Control
- 2.12. Chip-Level Reset
- 2.13. Power-On State Machine
- 2.14. Subsystem Resets
- 2.15. Clocks
- 2.16. Crystal Oscillator (XOSC)
- 2.17. Ring Oscillator (ROSC)
- 2.18. PLL
- 2.19. GPIO
- 2.20. Sysinfo
- 2.21. Syscfg
- 2.22. TBMAN
- Chapter 3. PIO
- Chapter 4. Peripherals
- 4.1. USB
- 4.2. UART
- 4.3. I2C
- 4.3.1. Features
- 4.3.2. IP Configuration
- 4.3.3. I2C Overview
- 4.3.4. I2C Terminology
- 4.3.5. I2C Behaviour
- 4.3.6. I2C Protocols
- 4.3.7. Tx FIFO Management and START, STOP and RESTART Generation
- 4.3.8. Multiple Master Arbitration
- 4.3.9. Clock Synchronization
- 4.3.10. Operation Modes
- 4.3.11. Spike Suppression
- 4.3.12. Fast Mode Plus Operation
- 4.3.13. Bus Clear Feature
- 4.3.14. IC_CLK Frequency Configuration
- 4.3.15. DMA Controller Interface
- 4.3.16. Operation of Interrupt Registers
- 4.3.17. List of Registers
- 4.4. SPI
- 4.5. PWM
- 4.6. Timer
- 4.7. Watchdog
- 4.8. RTC
- 4.9. ADC and Temperature Sensor
- 4.10. SSI
- 4.10.1. Overview
- 4.10.2. Features
- 4.10.3. IP Modifications
- 4.10.4. Clock Ratios
- 4.10.5. Transmit and Receive FIFO Buffers
- 4.10.6. 32-Bit Frame Size Support
- 4.10.7. SSI Interrupts
- 4.10.8. Transfer Modes
- 4.10.9. Operation Modes
- 4.10.10. Partner Connection Interfaces
- 4.10.11. DMA Controller Interface
- 4.10.12. APB Interface
- 4.10.13. List of Registers
- Chapter 5. Electrical and Mechanical
- Appendix A: Register Field Types
- Appendix B: Errata
- Appendix C: Documentation Release History
WARNING
If no IRQ is configured before going into dormant mode the ROSC will never restart.
See Section 2.11.5.2 for a some examples of dormant mode.
2.17.8. List of Registers
The ROSC registers start at a base address of 0x40060000 (defined as ROSC_BASE in SDK).
Table 274. List of
ROSC registers
Offset Name Info
0x00 CTRL Ring Oscillator control
0x04 FREQA Ring Oscillator frequency control A
0x08 FREQB Ring Oscillator frequency control B
0x0c DORMANT Ring Oscillator pause control
0x10 DIV Controls the output divider
0x14 PHASE Controls the phase shifted output
0x18 STATUS Ring Oscillator Status
0x1c RANDOMBIT Returns a 1 bit random value
0x20 COUNT A down counter running at the ROSC frequency which counts to
zero and stops.
ROSC: CTRL Register
Offset: 0x00
Description
Ring Oscillator control
Table 275. CTRL
Register
Bits Name Description Type Reset
31:24 Reserved. - - -
23:12 ENABLE On power-up this field is initialised to ENABLE
The system clock must be switched to another source
before setting this field to DISABLE otherwise the chip will
lock up
The 12-bit code is intended to give some protection
against accidental writes. An invalid setting will enable the
oscillator.
0xd1e → DISABLE
0xfab → ENABLE
RW -
RP2040 Datasheet
2.17. Ring Oscillator (ROSC) 247