CY7C63001A-SC Просмотр технического описания (PDF) - Cypress Semiconductor

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CY7C63001A-SC

Universal Serial Bus Microcontroller

Cypress Semiconductor 

FOR

FOR

CY7C63000A/CY7C63001A

CY7C63100A/CY7C63101A

5.1.3 Data Memory Organization

The USB Controller includes 128 bytes of data RAM. The upper 16 bytes of the data memory are used as USB FIFOs for Endpoint

0 and Endpoint 1. Each endpoint is associated with an 8-byte FIFO.

The USB controller includes two pointers into data RAM, the Program Stack Pointer (PSP) and the Data Stack Pointer (DSP).

The value of PSP after reset is 0x00. The PSP increments by 2 whenever a CALL instruction is executed and it decrements by

2 whenever a RET instruction is used.

The DSP pre-decrements by 1 whenever a PUSH instruction is executed and it increments by 1 after a POP instruction is used.

The default value of the DSP after reset is 0x00, which would cause the first PUSH to write into USB FIFO space for Endpoint 1.

Therefore, the DSP should be mapped to a location such as 0x70 before initiating any data stack operations. Refer to the Reset

section for more information about DSP remapping after reset. Figure 5-2 illustrates the Data Memory Space.

after reset

DSP

PSP

Address

0x00

0x02

user

firmware

0x04

DSP

0x70

USB FIFO - Endpoint 0

0x77

0x78

USB FIFO - Endpoint 1

0x7F

Figure 5-2. Data Memory Space

Document #: 38-08026 Rev. **

Page 8 of 31

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