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3 # Author: Gary Carlson (gcarlson@carlson-minot.com) #
4 # Generated for Atmel AT91SAM9G20-EK evaluation board using Atmel SAM-ICE (J-Link) version 8. #
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8 # FIXME use some standard target config, maybe create one from this
10 # source [find target/...cfg]
12 # Define basic characteristics for the CPU. The AT91SAM9G20 processor is a subtle variant of
13 # the AT91SAM9260 and shares the same tap ID as it.
15 set _CHIPNAME at91sam9g20
16 set _FLASHTYPE nandflash_cs3
18 set _CPUTAPID 0x0792603f
20 # Set reset type. Note that the AT91SAM9G20-EK board has the trst signal disconnected. Therefore
21 # the reset needs to be configured for "srst_only". If for some reason, a zero-ohm jumper is
22 # added to the board to connect the trst signal, then this parameter may need to be changed.
24 reset_config srst_only
26 # Set up the CPU and generate a new jtag tap for AT91SAM9G20.
28 jtag newtap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_CPUTAPID
30 # Use caution changing the delays listed below. These seem to be
31 # affected by the board and type of JTAG adapter. A value of 200 ms seems
32 # to work reliably for the configuration listed in the file header above.
34 adapter_nsrst_delay 200
37 # Set fallback clock to 1/6 of worst-case clock speed (which would be the 32.768 kHz slow clock).
41 set _TARGETNAME $_CHIPNAME.cpu
42 target create $_TARGETNAME arm926ejs -endian $_ENDIAN -chain-position $_TARGETNAME
44 # Establish internal SRAM memory work areas that are important to pre-bootstrap loaders, etc. The
45 # AT91SAM9G20 has two SRAM areas, one starting at 0x00200000 and the other starting at 0x00300000.
46 # Both areas are 16 kB long.
48 #$_TARGETNAME configure -work-area-phys 0x00200000 -work-area-size 0x4000 -work-area-backup 1
49 $_TARGETNAME configure -work-area-phys 0x00300000 -work-area-size 0x4000 -work-area-backup 1
51 # If you don't want to execute built-in boot rom code (and there are good reasons at times not to do that) in the
52 # AT91SAM9 family, the microcontroller is a lump on a log without initialization. Because this family has
53 # some powerful features, we want to have a special function that handles "reset init". To do this we declare
54 # an event handler where these special activities can take place.
57 $_TARGETNAME configure -event reset-init {at91sam9g20_reset_init}
58 $_TARGETNAME configure -event reset-start {at91sam9g20_reset_start}
60 # NandFlash configuration and definition
62 nand device nandflash_cs3 at91sam9 $_TARGETNAME 0x40000000 0xfffffe800
65 at91sam9 rdy_busy 0 0xfffff800 13
66 at91sam9 ce 0 0xfffff800 14
68 proc read_register {register} {
70 mem2array result 32 $register 1
74 proc at91sam9g20_reset_start { } {
76 # Make sure that the the jtag is running slow, since there are a number of different ways the board
77 # can be configured coming into this state that can cause communication problems with the jtag
78 # adapter. Also since this call can be made following a "reset init" where fast memory accesses
79 # are enabled, need to temporarily shut this down so that the RSTC_MR register can be written at slower
80 # jtag speed without causing GDB keep alive problem.
82 arm7_9 fast_memory_access disable
83 adapter_khz 2 # Slow-speed oscillator enabled at reset, so run jtag speed slow.
84 halt # Make sure processor is halted, or error will result in following steps.
86 mww 0xfffffd08 0xa5000501 # RSTC_MR : enable user reset.
89 proc at91sam9g20_reset_init { } {
91 # At reset AT91SAM9G20 chip runs on slow clock (32.768 kHz). To shift over to a normal clock requires
92 # a number of steps that must be carefully performed. The process outline below follows the
93 # recommended procedure outlined in the AT91SAM9G20 technical manual.
95 # Several key and very important things to keep in mind:
96 # The SDRAM parts used currently on the Atmel evaluation board are -75 grade parts. This
97 # means the master clock (MCLK) must be at or below 133 MHz or timing errors will occur. The processor
98 # core can operate up to 400 MHz and therefore PCLK must be at or below this to function properly.
100 mww 0xfffffd44 0x00008000 # WDT_MR : disable watchdog.
102 # Enable the main 18.432 MHz oscillator in CKGR_MOR register.
103 # Wait for MOSCS in PMC_SR to assert indicating oscillator is again stable after change to CKGR_MOR.
105 mww 0xfffffc20 0x00004001
106 while { [expr [read_register 0xfffffc68] & 0x01] != 1 } { sleep 1 }
108 # Set PLLA Register for 792.576 MHz (divider: bypass, multiplier: 43).
109 # Wait for LOCKA signal in PMC_SR to assert indicating PLLA is stable.
111 mww 0xfffffc28 0x202a3f01
112 while { [expr [read_register 0xfffffc68] & 0x02] != 2 } { sleep 1 }
114 # Set master system clock prescaler divide by 6 and processor clock divide by 2 in PMC_MCKR.
115 # Wait for MCKRDY signal from PMC_SR to assert.
117 mww 0xfffffc30 0x00000101
118 while { [expr [read_register 0xfffffc68] & 0x08] != 8 } { sleep 1 }
120 # Now change PMC_MCKR register to select PLLA.
121 # Wait for MCKRDY signal from PMC_SR to assert.
123 mww 0xfffffc30 0x00001302
124 while { [expr [read_register 0xfffffc68] & 0x08] != 8 } { sleep 1 }
126 # Processor and master clocks are now operating and stable at maximum frequency possible:
127 # -> MCLK = 132.096 MHz
128 # -> PCLK = 396.288 MHz
130 # Switch over to adaptive clocking.
134 # Enable faster DCC downloads and memory accesses.
136 arm7_9 dcc_downloads enable
137 arm7_9 fast_memory_access enable
139 # To be able to use external SDRAM, several peripheral configuration registers must
140 # be modified. The first change is made to PIO_ASR to select peripheral functions
141 # for D15 through D31. The second change is made to the PIO_PDR register to disable
142 # this for D15 through D31.
144 mww 0xfffff870 0xffff0000
145 mww 0xfffff804 0xffff0000
147 # The EBI chip select register EBI_CS must be specifically configured to enable the internal SDRAM controller
148 # using CS1. Additionally we want CS3 assigned to NandFlash. Also VDDIO is connected physically on
149 # the board to the 3.3 VDC power supply so set the appropriate register bit to notify the micrcontroller.
151 mww 0xffffef1c 0x000100a
153 # The AT91SAM9G20-EK evaluation board has built-in NandFlash. The exact physical timing characteristics
154 # for the memory type used on the current board (MT29F2G08AACWP) can be established by setting
155 # a number of registers. The first step involves setting up the general I/O pins on the processor
156 # to be able to interface and support the external memory.
158 mww 0xfffffc10 0x00000010 # PMC_PCER : enable PIOC clock
159 mww 0xfffff800 0x00006000 # PIOC_PER : enable PIO function for 13(RDY/~BSY) and 14(~CS)
160 mww 0xfffff810 0x00004000 # PIOC_OER : enable output on 14
161 mww 0xfffff814 0x00002000 # PIOC_ODR : disable output on 13
162 mww 0xfffff830 0x00004000 # PIOC_SODR : set 14 to disable NAND
164 # The exact physical timing characteristics for the memory type used on the current board
165 # (MT29F2G08AACWP) can be established by setting four registers in order: SMC_SETUP3,
166 # SMC_PULSE3, SMC_CYCLE3, and SMC_MODE3. Computing the exact values of these registers
167 # is a little tedious to do here. If you have questions about how to do this, Atmel has
168 # a decent application note #6255B that covers this process.
170 mww 0xffffec30 0x00020002 # SMC_SETUP3 : 2 clock cycle setup for NRD and NWE
171 mww 0xffffec34 0x04040404 # SMC_PULSE3 : 4 clock cycle pulse for all signals
172 mww 0xffffec38 0x00070006 # SMC_CYCLE3 : 7 clock cycle NRD and 6 NWE cycle
173 mww 0xffffec3C 0x00020003 # SMC_MODE3 : NRD and NWE control, no NWAIT, 8-bit DBW,
175 mww 0xffffe800 0x00000001 # ECC_CR : reset the ECC parity registers
176 mww 0xffffe804 0x00000002 # ECC_MR : page size is 2112 words (word is 8 bits)
178 # Identify NandFlash bank 0.
180 nand probe nandflash_cs3
182 # The AT91SAM9G20-EK evaluation board has build-in serial data flash also.
184 # Now setup SDRAM. This is tricky and configuration is very important for reliability! The current calculations
185 # are based on 2 x Micron MT48LC16M16A2-75 memory (4 M x 16 bit x 4 banks). If you use this file as a reference
186 # for a new board that uses different SDRAM devices or clock rates, you need to recalculate the value inserted
187 # into the SDRAM_CR register. Using the memory datasheet for the -75 grade part and assuming a master clock
188 # of 132.096 MHz then the SDCLK period is equal to 7.6 ns. This means the device requires:
190 # CAS latency = 3 cycles
197 # 9 column, 13 row, 4 banks
198 # refresh equal to or less then 7.8 us for commerical/industrial rated devices
200 # Thus SDRAM_CR = 0xa6339279
202 mww 0xffffea08 0xa6339279
204 # Next issue a 'NOP' command through the SDRAMC_MR register followed by writing a zero value into
205 # the starting memory location for the SDRAM.
207 mww 0xffffea00 0x00000001
210 # Issue an 'All Banks Precharge' command through the SDRAMC_MR register followed by writing a zero
211 # value into the starting memory location for the SDRAM.
213 mww 0xffffea00 0x00000002
216 # Now issue an 'Auto-Refresh' command through the SDRAMC_MR register. Follow this operation by writing
217 # zero values eight times into the starting memory location for the SDRAM.
229 # Almost done, so next issue a 'Load Mode Register' command followed by a zero value write to the
230 # the starting memory location for the SDRAM.
235 # Signal normal mode using the SDRAMC_MR register and follow with a zero value write the the starting
236 # memory location for the SDRAM.
241 # Finally set the refresh rate to about every 7 us (7.5 ns x 924 cycles).
243 mww 0xffffea04 0x0000039c