at91sam9260-cj ATMEL Corporation, at91sam9260-cj Datasheet - Page 210

• Manufacturer Part Number: at91sam9260-cj
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

6221G–ATARM–31-Jan-08
After initialization, the SDRAM devices are fully functional.
Note:
6. An All Banks Precharge command is issued to the SDRAM devices. The application
7. Eight auto-refresh (CBR) cycles are provided. The application must set the Mode to 4 in
8. A Mode Register set (MRS) cycle is issued to program the parameters of the SDRAM
9. For mobile SDRAM initialization, an Extended Mode Register set (EMRS) cycle is
10. The application must go into Normal Mode, setting Mode to 0 in the Mode Register and
11. Write the refresh rate into the count field in the SDRAMC Refresh Timer register.
must set Mode to 2 in the Mode Register and perform a write access to any SDRAM
address.
the Mode Register and perform a write access to any SDRAM location eight times.
devices, in particular CAS latency and burst length. The application must set Mode to 3
in the Mode Register and perform a write access to the SDRAM. The write address
must be chosen so that BA[1:0] are set to 0. For example, with a 16-bit 128 MB SDRAM
(12 rows, 9 columns, 4 banks) bank address, the SDRAM write access should be done
at the address 0x20000000.
issued to program the SDRAM parameters (TCSR, PASR, DS). The application must
set Mode to 5 in the Mode Register and perform a write access to the SDRAM. The
write address must be chosen so that BA[1] or BA[0] are set to 1. For example, with a
16-bit 128 MB SDRAM, (12 rows, 9 columns, 4 banks) bank address the SDRAM write
access should be done at the address 0x20800000 or 0x20400000.
performing a write access at any location in the SDRAM.
(Refresh rate = delay between refresh cycles). The SDRAM device requires a refresh
every 15.625 µs or 7.81 µs. With a 100 MHz frequency, the Refresh Timer Counter
Register must be set with the value 1562(15.652 µs x 100 MHz) or 781(7.81 µs x 100
MHz).
1. It is strongly recommended to respect the instructions stated in
cess in order to be certain that the subsequent commands issued by the SDRAMC will be
taken into account.
AT91SAM9260
Step 5
of the initialization pro-
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