PXD20RM Datasheet, PDF (583/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

– Arbiter 6: Looks for highest priority precharge-for-write command
— After the first prioritization, the next round of arbitrating between the different arbiters is done.
A fixed-priority schema is followed:
– Read and write commands have highest priority
– Activate has next-highest priority
– Precharge has lowest priority
– The DRAM is in read or write mode. In read mode, reads have priority over writes. In write
mode, writes have priority over read.
– DRAM only switches from read to write mode or vice-versa if:
A high-priority write is found, and the write buffer is full.
A high-priority read is found.
The device is in read mode, but no more reads pending
The device is in write mode, but no more writes pending.
• Write buffer contains five 32-byte entries.
• Supports 16- and 32-bit-wide Mobile-DDR/DDR1/DDR2 and DRAM devices
• Controller supports two chip selects, 8 banks per chip select (16 banks total).
• Supports dynamic on-die termination in the host device and in the DRAM.
13.3 Memory map and register definition
13.3.1 Memory map
Table 13-1. DRAMC memory map
Offset from
DRAM_BASE
Register
0x000
DRAMC_SCR—DRAMC System Configuration Register
0x004
DRAMC_TC0—DRAMC Time Config0 Register
0x008
DRAMC_TC1—DRAMC Time Config1 Register
0x00C
DRAMC_TC2—DRAMC Time Config2 Register
0x010
DRAMC_CMD—DRAMC Command Register
0x014
DRAMC_CCMD—DRAMC Compact Command Register
0x018–0x034 Reserved
0x038
0x03C
0x040
DRAMC_DQS_OC—DQS Config Offset Count Register
DRAMC_DQS_OT—DQS Config Offset Time Register
DRAMC_DQS_DS—DQS Delay Status Register
0x044–0x05F Reserved
0x060
DRAMC_EXTRA—DRAMC extra attributes
0x064–0xFFF Reserved
Access Reset Value
Location
R/W 0x1000_0000 on page 13-4
R/W 0x0000_0000 on page 13-8
R/W 0x0000_0000 on page 13-9
R/W 0x0000_0000 on page 13-9
R/W 0x0000_0000 on page 13-13
R/W 0x0000_0000 on page 13-13
R/W 0x0000_0000 on page 13-15
R/W 0x0000_0000 on page 13-16
R 0x0000_0000 on page 13-16
R/W 0x0000_0000 on page 13-17
Freescale Semiconductor
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
13-3