4.1. Memory maps

There are four memory maps available for the CT-R4F local memory and memory mapped peripherals. The memory map selected is determined by the REMAP[2:0] value in the CT_R4F_TC_CFG2 register. The value is set by the baseboard using the 4-wire serial interface to the CT-R4F. The remap options are:

REMAP = b000

This is the regular configuration memory map. In this configuration, the 512MB of local SDRAM memory appears aliased at the top of memory beginning at 0xE10A0000 and ending at 0xFFFFFFFF. The memory map is shown in Figure 4.1.

REMAP = b001

This configuration moves the local SDRAM and memory mapped peripherals down the memory map 1G, mapping the top 1G of memory to the CT-R4F AXI master port. This mode supports another slave tile at 0xF0000000. The 512MB of local SDRAM memory appears aliased beginning at 0xD10A0000 and ending at 0xEFFFFFFF. The memory map is shown in Figure 4.2.

REMAP = b010

In this configuration, the bottom 256MB of the memory map is mapped to the on-board SDRAM. The 512MB of local SDRAM memory is also aliased at the top of memory beginning at 0xE10A0000 and ending at 0xFFFFFFFF. The memory map is shown in Figure 4.3.

REMAP = b100

This configuration moves the local SDRAM and memory mapped peripherals down the memory map 1G, mapping the top 1G of memory to the CT-R4F AXI master port. This mode supports another slave tile at 0xF0000000. The bottom 256MB of the memory map is mapped to the on-board SDRAM. The 512MB of local SDRAM memory appears aliased beginning at 0xD10A0000 and ending at 0xEFFFFFFF. The memory map is shown in Figure 4.4.

Figure 4.1. Memory map (REMAP = 000)

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Figure 4.2. Memory map (REMAP = 001)

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Figure 4.3. Memory map (REMAP = 010)

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Figure 4.4. Memory map (REMAP = 100)

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