Cypress Semiconductor FX2LP Información técnica descargar pdf (Pagina 156)

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EZ-USB FX2 Technical Reference Manual

Page 8-20 EZ-USB FX2 Technical Reference Manual v2.1

Most of the Autopointer registers are in SFR Space for quick access; the data registers are avail-

able only in External Data space.

The Autopointers are configured using three bits in the AUTOPTRSETUP register: one bit

(APTREN) enables both autopointers, and two bits (one for each Autopointer, called APTR1INC

and APTR2INC, respectively) control whether or not the address increments for every Autodata

access.

Enabling the Autopointers has one side-effect: Any code access (an instruction fetch, for instance)

from addresses 0xE67B and 0xE67C will return the AUTODATA values, rather than the code-

memory values at these two addresses. This introduces a two-byte “hole” in the code memory.

There is no two-byte hole in the

data

memory at 0xE67B:E67C; the hole only appears in the

pro-

gram

memory.

Table 8-9. Registers that control the Autopointers

Address Register Name Function

SFR 0xAF AUTOPTRSETUP Increment/freeze, off-chip access enable

SFR 0x9A AUTOPTR1H Address high

SFR 0x9B AUTOPTR1L Address low

0xE67B XAUTODAT1 Data

SFR 0x9D AUTOPTR2H Address high

SFR 0x9E AUTOPTR2L Address low

0xE67C XAUTODAT2 Data

1 2 ... 151 152 153 154 155 156 157 158 159 160 161 ... 459 460

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