source: SVN/rincon/u-boot/board/gen860t/README @ 55

Last change on this file since 55 was 55, checked in by Tim Harvey, 22 months ago

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Signed-off-by: Tim Harvey <tharvey@…>

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1This directory contains board specific code for a generic MPC860T based
2embedded computer, called 'GEN860T'.  The design is generic in the sense that
3common, readily available components are used and that the architecture of the
4system is relatively straightforward:
5
6        One eight bit wide boot (FLASH) memory
7        32 bit main memory using SDRAM
8        DOC 2000+
9        Ethernet PHY
10        Some I2C peripheral devices: Atmel AT24C256 EEPROM, Maxim DS1337 RTC.
11        Some other miscellaneous peripherals
12
13NOTE: There are references to a XIlinx FPGA and Mil-Std 1553 databus in this
14port.  I guess the computer is not as generic as I first said 8)  However,
15these extras can be safely ignored.
16
17Given the GEN860T files, it should be pretty easy to reverse engineer the
18hardware configuration, if that's useful to you.  Hopefully, this code will
19be useful to someone as a basis for a port to a new system or as a head start
20on a custom design.  If you end up using any of this, I would appreciate
21hearing from you, especially if you discover bugs or find ways to improve the
22quality of this U-Boot port.
23
24Here are the salient features of the system:
25Clock                                           :       33.3 Mhz oscillator
26Processor core frequency        :       66.6 Mhz  if in 1:2:1 mode; can also run 1:1
27Bus frequency                           :       33.3 Mhz
28
29Main memory:
30        Type    : SDRAM
31        Width   : 32 bits
32        Size    : 64 mibibytes
33        Chip    : Two Micron MT48LC16M16A2TG-7E
34        CS              : MPC860T CS1*/UPMA
35        UPMA CONNECTIONS:
36                SDRAM A10       : GPLA0*
37                SDRAM CAS*      : GPLA2*
38                SDRAM WE*       : GPLA3*
39                SDRAM RAS*      : GPLA4*
40
41Boot memory:
42        Type    : FLASH
43        Width   : 8 bits
44        Size    : 16 mibibytes
45        Chip    : One Intel 28F128J3A (StrataFlash)
46        CS              : MPC860T CS0*/GPCM (this is the "boot" chip select)
47
48EEPROM memory:
49        Type    : Serial I2C EEPROM
50        Width   : 8 bits
51        Size    : 32 kibibytes
52        Chip    : One Atmel AT25C256
53        CS              : 0x50 (external I2C address pins on device are tied to GND)
54
55Filesystem memory:
56        Type    : NAND FLASH (Toshiba)
57        Width   : 8 bits (i.e. interface to DOC is 8 bits)
58        Size    : 32 mibibytes
59        Chip    : One DiskOnCHip Millenium Plus (DOC 2000+)
60        CS              : MPC860T CS2*/GPCM
61
62Network support:
63        MAC             : MPC86OT FEC (Fast Ethernet Controller)
64        PHY             : Intel LXT971A
65        MII Addr: 0x0 (hardwired on the board)
66        MII IRQ :
67
68Console:
69        RS-232 on SMC1 (Maxim MAX3232 LVCMOS-RS232 level shifter)
70
71Real Time Clock:
72        Type    : Low power, I2C interface
73        Chip    : Maxim DS1337
74        CS              : Address 0x68 on I2C bus
75
76        The MPC860T's internal RTC has a defect in Mask rev D that increases
77        the current drain on the KAPWR line to 10 mA.  Since this is an
78        unreasonable amount of current draw for a RTC, and Motorola does not
79        plan to fix this in future mask revisions, a serial (I2C) RTC that
80        works has been included instead.  NOTE that the DS1337 can be
81        configured to output a 32768 Hz clock while the main power is on.
82        This clock output has been routed to the MPC860T's EXTAL pin to allow
83        the internal RTC to be used.  NOTE also that due to yet another
84        defect in the rev D mask, the RTC does not operate reliably when the
85        internal RTC divisor is set to use a 32768 Hz reference.  So just use
86        the I2C RTC.
87
88Miscellaneous:
89        Xilinx Virtex FPGA on CS3*/GPCM.
90        Virtex FPGA slave SelectMap interface on cs4*/UPMB.
91        Mil-Std 1553 databus interface on CS5*/GPCM.
92        Audio sounder (beeper) with digital volume control connected to SPKROUT.
93
94SC variant:
95        A reduced-feature version of the GEN860T port is also supported: GEN860T_SC.
96        The 'SC' variant only provides support for the Virtex FPGA, SDRAM main
97        memory, EEPROM and flash memory.  The system clock frequency is reduced
98        to 24 MHz.
99
100Issues:
101        The DOC 2000+ returns 0x40 as its device ID when probed using the method
102        desxribed in the DOC datasheet.  Unfortunately, the U-Boot DOC driver
103        does not recognize this device.  As of this writing, it seems that MTD
104        does not support the DOC 2000+ either.
105
106Status:
107        Everything appears to work except DOC support. As of this writing,
108        David Woodhouse has stated on the MTD mailing list that he has no
109        knowledge of the DOC Millineum Plus and therfore there is no support
110        in MTD for this device.  I wish I had known this sooner :(
111
112The GEN860T board specific files and configuration is based on the work
113of others who have contributed to U-Boot. The copyright and license notices
114of these authors have been retained wherever their code has been reused.
115All new code to support the GEN860T board is:
116
117        (C) Copyright 2001-2003
118        Keith Outwater (keith_outwater@mvis.com)
119
120and the following license applies:
121
122This program is free software; you can redistribute it and/or
123modify it under the terms of the GNU General Public License as
124published by the Free Software Foundation; either version 2 of
125the License, or (at your option) any later version.
126
127This program is distributed in the hope that it will be useful,
128WITHOUT ANY WARRANTY; without even the implied warranty of
129MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
130GNU General Public License for more details.
131
132You should have received a copy of the GNU General Public License
133along with this program; if not, write to the Free Software
134Foundation, Inc., 59 Temple Place, Suite 330, Boston,
135MA 02111-1307 USA
136
137Thanks to Wolfgang Denk for a great software package and to everyone
138who contributed to its development.
139
140Keith Outwater
141Sr. Staff Engineer
142Microvision, Inc.
143<keith_outwater@mvis.com>
144<outwater@eskimo.com>
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