Shared memory architecture

• US 7,127,563 B2
• Filed: 09/07/2005
• Issued: 10/24/2006
• Est. Priority Date: 11/08/2001
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Rader, Sheila M.
• Primary Examiner(s): MCLEAN MAYO, KIMBERLY N
• Application Number:
  US11/220,735
• Publication Number:
  US 20060004976A1
• Time in Patent Office: 412 Days
• Field of Search: 711/148, 711/150, 711/154, 711/149
• US Class Current: 711/148
• CPC Class Codes: G06F 13/1684 using multiple buses

Abstract

A wireless communications architecture having first and second synchronous memory devices coupled to a virtual channel memory controller by corresponding first and second data buses, and a shared address and control bus interconnecting the virtual channel memory controller and the first and second synchronous memory devices. The first and second synchronous memory devices are addressed with the shared address bus, and the first and second memory locations are accessed via the first and second data buses, respectively.

Claims

1. A shared memory system architecture, comprising:

a memory controller module;

first and second processor cores coupled to the memory controller module;

a first memory device coupled to the memory controller module by a first data bus;

a second memory device coupled to the memory controller module by a second data bus;

a shared address and control bus interconnecting the memory controller module and the first and second memory devices;

a group of shared memory space access registers defining access permission to shared memory space.

2. The architecture of claim 1, wherein:

the memory controller module includes address bus arbitration logic, first and second memory controllers, and a multiplexer;

the address bus arbitration loge is coupled to first and second memory controllers, and the multiplexer interconnects the first and second memory controllers to the shared address and control bus.

3. The architecture of claim 1, wherein the first memory device and the second memory device is one of a SRAM, SDRAM, Flash, or ROM memory.

4. The architecture of claim 1 further comprising a first direct memory access channel coupled to the memory controller module.

5. The architecture of claim 1 further comprising a display controller coupled to the memory controller module.

6. The architecture of claim 1 wherein the first processor core is a digital signal processor and the second processor core is a RISC processor.

7. The architecture of claim 1 wherein the memory controller module and the first and second processor cores are disposed on a single integrated circuit.

8. The architecture of claim 1 wherein the first memory device and the second memory device are different types of memory devices.

9. The architecture of claim 1 wherein the first memory device is characterized as a synchronous memory device and the second memory device is characterized as a synchronous memory device.

10. The architecture of claim 1 wherein the memory controller module includes a group of shared memory space access registers interconnecting first and second processor core memory access register blocks, the first processor core memory access register block coupled to the first processor core, the second processor core memory access register block coupled to the second processor core.

11. The architecture of clam 1 further comprising:

a first processor core memory access register block coupled to the first processor core;

a second processor core memory access register block coupled to the second processor core;

wherein the first processor core memory access register block and the second processor core memory access register block define memory access permission and enforce protected memory areas of the first and second processor cores.

12. A method comprising:

addressing first and second memory devices with a shared address bus interconnecting the first and second memory devices and a memory controller module;

transferring data between the first memory device and the memory controller module on a first data bus;

transferring data between the second memory device and the memory controller module on a second data bus;

conveying access permission to shared memory space with a group of registers indicating shared memory space policy;

facilitating communication between first and second processor cores with the shared memory space.

13. The method of claim 12 wherein the facilitating communication between first and second processor cores with the shared memory space further includes facilitating communication between the first and second processor cores with the shared memory space by passing data by reference.

14. The method of claim 12, concurrently accessing the first and second memory devices.

15. The method of claim 12, addressing the first memory device with the shared address bus, transferring data between the first memory device and the memory controller module in response to addressing the first memory device, addressing the second memory device with the shared address bus after addressing the first memory device, transferring data between the second memory device and the memory controller module in response to addressing the second memory device while transferring data between the first memory device and the memory controller module.

16. The method of claim 12, reducing latency by addressing one of the first and second memory devices while accessing the same memory device addressed.

17. The method of claim 12, reducing power consumption by not changing a state of the shared address bus during an interval between addressing the first and second memory devices.

18. The method of claim 12, addressing one of the first and second synchronous memory devices while accessing the first and second synchronous memory devices.

19. The method of claim 12, wherein the memory controller module and the first and second processor cores are disposed on a single integrated circuit.

20. A shared memory system architecture, comprising:

a memory controller module;

first and second processor cores coupled to the memory controller module;

wherein the memory controller module and the first and second processor cores are disposed on a single integrated circuit;

a first memory device coupled to the memory controller module by a first data bus;

a second memory device coupled to the memory controller module by a second data bus;

a group of shared memory space access registers defining access permission to shared memory space, the group of shared memory space access registers disposed on the single integrated circuit.

21. The architecture of claim 20, wherein:

the memory controller module includes address bus arbitration logic, first and second memory controllers, and a multiplexer, wherein the address bus arbitration logic, the first and second memory controllers, and the multiplexer disposed on the single integrated circuit;

the address bus arbitration logic is coupled to the first and second memory controllers, and the multiplexer interconnects the first and second memory controllers to the shared address and control bus.

22. The architecture of claim 20, a direct memory access channel coupled to the memory controller module, the direct memory access channel disposed on the single integrated circuit.

23. The architecture of claim 20, a display controller coupled to the memory controller module, the display controller disposed on the single integrated circuit.