MAC7200 datasheet(469/976 Pages) FREESCALE

469 / 976 page

Platform RAM Array Controller (PRAM_CTL)

MAC7200 Microcontroller Family Reference Manual, Rev. 2

Freescale Semiconductor

391

Figure 19-7. Less than 32-bit writes

19.2.3.5.3

Unaligned Writes

The PRAM_CTL controller is compliant with the ARMv6 AMBA Extensions specification with regard to

section "3.1 Byte Strobes." In essence, this document specifies that the valid byte strobes (HBSTRB[7:0])

are determined by the container which is determined by HADDR and HSIZE. The size of the transfer will

be sufficient to cover all bytes being written and will cover more bytes in the case of a mis-aligned transfer.

The address of the transfer will be rounded down to the nearest boundary of the size of the transaction.

Table 19-7 below is a replica of the two tables shown in the ARMv6 document. The 32-bit implementation

can be inferred from this table as well.

It should be noted that unaligned writes always generate read/modify/write operations in the pram

controller in order to preserve the validity of the ECC codeword.

Table 19-7. Unaligned Writes

Transfer description

HADDR

HSIZE[2:0]

HBSTRB[7:0]

HUNALIGN

8-bit access to 0x1000

0x1000

0x0

00000001

8-bit access to 0x1003

0x1003

0x0

00001000

234

addr y

addr z

nonseq

idle

byte

data y

data z

addr y

addr z

addr y

addr z

2'b10

2'b11

2'b01

2'b10

2'b11

2'b01

2'b11

data y

data z

data y

data z

data y

data z

hclk

haddr

htrans

hwrite

hsize

hready

hwdata

pram_addr

pram_we

pram_cs_b

pram_rdata

pram_wdata

late write buffer

MAC7200 Datasheet(PDF) 469 Page - Freescale Semiconductor, Inc

MAC7200 Datasheet(HTML) 469 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL