SH7243 datasheet(409/1726 Pages) RENESAS

409 / 1726 page

Section 9 Bus State Controller (BSC)

Rev. 1.00 Jun. 26, 2008 Page 379 of 1692

REJ09B0393-0100

bus, the I bus, and the peripheral bus are synchronized with the I

φ, Bφ, and Pφ clock, respectively.

Figure 9.44 shows an example of the timing of write access to a peripheral bus when I

φ:Bφ:Pφ =

4:4:1. C bus whose are connected to CPU outputs data in synchronization with I

φ. A data transfer

from C bus to I bus requires a period of 2I

φ + Bφ when Iφ:Bφ = 1:1. The transfer from the I bus to

the peripheral bus, when B

φ:Pφ = 4:1, there are 4 clocks exist between Pφ × 1. Thus maximum the

period of 4

× Bφ is required corresponds to the rising edge of Pφ, which the timing of data output

to the peripheral bus from the I bus. When I

φ: Bφ = 4:2, transfer of data from the I bus to the

peripheral bus takes (3

+ n) × Iφ (4 × Bφ is indicated in figure 9.44). The relation between the

timing of data output to the I bus and the rising edge of P

φ depends on the state of program

execution. In the case shown in the figure, where n = 0 and m = 3, the time required for access is 2

× Iφ + 4 × Bφ + 2 × Pφ.

C bus

I bus

Peripheral bus

(1 + m)

× Bφ

× Pφ

(2 + n)

× Iφ

Figure 9.44 Timing of Write Access to On-Chip Peripheral I/O Registers

When I

φ;Bφ:Pφ = 4:4:1

Figure 9.45 shows an example of timing of read access to the peripheral bus when I

φ:Bφ:Pφ =

4:2:1. Transfer from the C bus to the peripheral bus is performed in the same way as for write

access. In the case of reading, however, values output onto the peripheral bus must be transferred

to the CPU. Although transfers from the peripheral bus to the I bus and from the I bus to the C bus

are performed in synchronization with the rising edge of the respective bus clocks, a period of (2

× Iφ is actually required because Iφ ≥ Bφ≥ Pφ. In the case shown in the figure 9.45, where n = 1,

m = 1, and l = 1, the time required for access is 3

× Iφ + 2 × Bφ + 2 × Pφ + 3 × Iφ.

SH7243 Datasheet(PDF) 409 Page - Renesas Technology Corp

SH7243 Datasheet(HTML) 409 Page - Renesas Technology Corp

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