CY7C63001C-PXC Просмотр технического описания (PDF) - Cypress Semiconductor

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CY7C63001C-PXC

Universal Serial Bus Microcontroller

Cypress Semiconductor 

CY7C63001C

CY7C63101C

6.1.3 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 incre-

ments by 2 whenever a CALL instruction is executed and it

decrements by 2 whenever a RET instruction is used.

after reset

DSP

PSP

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 opera-

tions. Refer to the Reset section for more information about

DSP remapping after reset. Figure 6-2 illustrates the Data

Memory Space.

Address

0x00

0x02

user

firmware

0x04

DSP

0x70

USB FIFO - Endpoint 0

0x77

0x78

USB FIFO - Endpoint 1

0x7F

Figure 6-2. Data Memory Space

Document #: 38-08026 Rev. *B

Page 5 of 28

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