Siemens ERTEC200 - Manual (Page 74)

7 Local Bus Unit (LBU).
The ERTEC 200 can also be operated from an external host processor. The LBU bus interfaces are available for this
purpose:
The bus system is selected using the CONFIG[2] input pin.
CONFIG[2] = 0
LBU bus system is active
CONFIG[2] = 1 LBU bus system is inactive (supplemental function PHY debug, ETM trace, GPIO[44:32] can be
activated)
The LBU is a 16-bit data interface.
The following signal pins are available for the LBU on the ERTEC 200.
•
Data bus 16 bit LBU_D[15 : 0]
•
Address bus 21 bit LBU_A[20 : 0]
• Memory
CS 1 LBU_CS_M_N
• Register
CS 1 LBU_CS_R_N
• RD/WR
config 1 LBU_CFG
•
RD/WR 2 LBU_WR_N / LBU_RD_N
•
Ready 2 LBU_POL_RDY, LBU_RDY_N
• Byte
selection 2 LBU_BE[1 : 0]
•
Page segment selection 2 LBU_SEG[1 : 0]
• Interrupt
outputs 2 LBU_IRQ0_N, LBU_IRQ1_N
Four different pages within the ERTEC 200 can be accessed via the LBU.
Each page can be set individually.
The settings for the four pages are made via the LBU page registers. Five page registers are available per page. These
registers are used for the size, offset, and access width settings of the page. The "LBU_CS_R_N" chip select signal can
be used to access the page registers.
The following settings are possible for each page:
•
Access size of a page between 256 bytes and 2 Mbytes with 2-page range register
•
Offset (segment) of page in 4-Gbyte address area with 2-page offset register
•
Access type (data bit width) with 1 page control register
After the page register has been configured, the ERTEC 200 internal address area is accessed via the LBU_CS_M_N
chip select signal.
The LBU supports accesses to the address area with separate read and write cables or with a common read/write cable.
The access type is set using the Config[5] configuration input.
CONFIG[5] RD/WR Control
0 Separate RD/WR cable
1 LBU_WR_N has RD/WR control
The polarity of the ready signal is set via the Config[6] configuration input.
CONFIG[6] LBU_RDY_N
0 Low active
1 High active
LBU_RDY_N is a tristate output and must be pulled to his “ready” level by an external pull-down or pull-up resistor.
During an access from the LBU-Interface to the ERTEC 200 (CS with RD or WR activ) , the LBU_RDY_N switched to
inactiv (Wait) first. LBU_RDY_N will be active for a 50 MHz-Clock if data will be read or write. After that LBU_RDY_N
switched back to tristate. The external Pull- (up/down) resistor drives the ready state.
Copyright © Siemens AG 2007. All rights reserved. 74 ERTEC 200 Manual
Technical data subject to change Version 1.1.0