Rev.2.00 Oct 16, 2006 page 340 of 354
REJ09B0340-0200
M30245 Group
4. External Buses
4.4 Connectable Memories
4.4.1 Operation Frequency and Access Time
Connectable memories depend upon the BCLK frequency f(BCLK). The frequency of f(BCLK) is equal to
that of the BCLK, and is contingent on the oscillator's frequency and on the settings in the system clock
select bits (bit 6 of address 0006
16
, and bits 6 and 7 of address 0007
16
).
The following are the conditional equations for the connections. Meet these conditions minimally. Fig-
ures 4.4.1 and 4.4.2 show the relation between the frequency of BCLK and memory.
(1) Read cycle time (tCR)/write cycle time (tCW)
Read cycle time (tCR) and write cycle time (tCW) must satisfy the following conditional expressions:
• With the Wait option cleared
tCR < 10
9
/f(BCLK) and tCW < 2
×
10
9
/f(BCLK)
(When CSxW = 1 read: one cycle of BCLK write: two cycles of BCLK)
• With the Wait option selected
tCR < (m+1)
×
10
9
/f(BCLK) and tCW < (m+1)
×
10
9
/f(BCLK)
(When CSxW = 0 and the number of the expansion waits is selected by the CSExW bit)
(m denotes the number of Wait states: m = “1” when 1 wait selected, “m = 2” when 2 waits selected,
and “m = 3” when 3 waits selected)
(2) Address access time [ta(A)]
Address access time [ta(A)] must satisfy the following conditional expressions:
(a) Vcc = 3.0 to 3.6 V
• With the Wait option cleared
ta(A) < 10
9
/f(BCLK) – 80(ns)*
• With the Wait option selected
ta(A) < (m+1)
×
10
9
/f(BCLK) – 80(ns)*
(m = “1” when 1 wait selected, “m = 2” when 2 waits selected, and “m = 3” when 3 waits selected)
*80(ns) = td(BCLK – AD) + tsu(DB – RD) – th(BCLK – RD)
= (address output delay time) + (data input setup time) – (RD signal output hold time)
(3) Chip select access time [ta(S)]
Chip select access time [ta(S)] must satisfy the following conditional expressions:
(a) Vcc = 3.0 to 3.6 V
• With the Wait option cleared
ta(S) < 10
9
/f(BCLK) – 80(ns)*
• With the Wait option selected
ta(S) < (m+1)
×
10
9
/f(BCLK) – 80(ns)*
(m = “1” when 1 wait selected, “m = 2” when 2 waits selected, and “m = 3” when 3 waits selected)
*80(ns) = td(BCLK – CS) + tsu(DB – RD) – th(BCLK – RD)
= (chip select output delay time) + (data input setup time) – (RD signal output hold time)
Содержание M16C FAMILY
Страница 12: ...Chapter 1 Hardware...
Страница 13: ...See M30245 group datasheet...
Страница 14: ...Chapter 2 Peripheral Functions Usage...
Страница 303: ...THIS PAGE IS BLANK FOR REASONS OF LAYOUT...
Страница 304: ...Chapter 3 Examples of Peripheral Functions Applications...
Страница 340: ...Chapter 4 External Buses...
Страница 361: ...THIS PAGE IS BLANK FOR REASONS OF LAYOUT...
Страница 362: ...Chapter 5 Standard Characteristics...
Страница 369: ...1753 Shimonumabe Nakahara ku Kawasaki shi Kanagawa 211 8668 Japan M30245 Group REJ09B0340 0200 User s Manual...