COM20022I Datasheet, PDF (64/83 Pages) SMSC Corporation – 10 MBPS ARCNET CONTROLLER WITH 2KX8 ON BOARD RAM

10 Mbps ARCNET (ANSI 878.1) Controller with 2Kx8 On-Board RAM
Datasheet
A0-A2
VALID
t1
t2
nCS
nRD
nWR
D0-D15
nIOCS16
t3
Note 3
t10
t6
t11
t5
t8
VALID DATA
VALID VALUE
t4
t9
Note 2
t7
t12
CASE 1: BUSTMG pin = HIGH and RBUSTMG bit = 0
Parameter
min
max units
t1 Address Setup to nRD Active
t2 ^{Address Hold from nRD Inactive}
t3 nCS Setup to nRD Active
t4 nCS Hold from nRD Inactive
t5 ^{Cycle Time (nRD Low to Next Time Low)}
t6 nRD Low to Valid Data
t7 nRD High to Data High Impedance
t8 nRD Low Width
t9 nRD High Width
t10 nWR to nRD Low
t11 nIOCS16 Output Delay from nCS Low
t12 nIOCS16 Hold Delay from nCS High
15
nS
10
nS
5**
nS
0
nS
4TARB*
nS
40** ^nS
0
20
nS
60
nS
20
nS
20
nS
40*** nS
0****
nS
* _{TARB is the Arbitration Clock Period}
TARB is identical to Topr if SLOW ARB = 0
TARB is twice Topr if SLOW ARB = 1
Topr is the period of operation clock. It depends on CKUP1 and CKUP0 bits
** ^{nCS may become active after control becomes active, but the access time (t6)}
will now be 45nS measured from the leading edge of nCS.
*** _{t11 is measured from the latest active (valid) timing among nCS, A0-A2.}
**** _{t12 is measured from the earliest inactive (invalid) timing among nCS, A0-A2.}
Note 1: The Microcontroller typically accesses the COM20022 on every other cycle.
Therefore, the cycle time specified in the microcontroller's datasheet
should be doubled when considering back-to-back COM20022 cycles.
Note 2: Read cycle for Address Pointer Low/High Registers occurring after a read from
Data Register requires a minimum of 5TARB from the trailing edge of nRD to the
leading edge of the next nRD.
Note 3: Read cycle for Address Pointer Low/High Registers occurring after a write to
Data Register requires a minimum of 5TARB from the trailing edge of nWR to the
leading edge of nRD.
Notes 2 and 3 are applied to an access to Data Register by DMA transfer.
Figure 8.5 - Non-Multiplexed Bus, 80XX-Like Control Signals; Read Cycle
Rev. 08-18-03
Page 64
DATASHEET
SMSC COM20022I