pef20320 Infineon Technologies Corporation, pef20320 Datasheet - Page 217

• Manufacturer Part Number: pef20320
• Description: Multichannel Network Interface Controller For Hdlc With 32 Channels
• Manufacturer: Infineon Technologies Corporation

5.3.1
As described in the previous section, the MUNICH32 in a steady state condition
consumes approximately 5% of the system bus bandwidth. Based on the conditions
previously described, a set of equations can be used to describe the MUNICH32 system
bus behavior. Other MUNICH32 systems can be evaluated using these equations. The
Bus occupancy is defined as the ratio of the time required for memory accesses for that
data to the time used to send the data. The two equations are defines as follows:
Time used for memory accesses:
transfer this
Time used to send the data is the number of transmitted bits per time slot multiplied by
the frame time:
From the previous example, the variables are assigned the following values:
Variable n
Value
User’s Manual
= Number of received bits plus transmitted bits multiplied by the time required to
= {([6 + (1 + m)]
= ((4 + n)
information to/from memory.
6 for receive descriptor access
5 for transmit descriptor access
(1 + m) for data access where m is the largest integer smaller (n – 1)/4
(n is the number of transmitted data bytes).
rc is the number of receive channels.
tc is the number of transmit channels.
(1 + 1/ba) is the bus arbitration time
sclk is the system clock (61 ns for 16.384 MHz)
NC is the number of memory clocks per bus operation (0ws = 4, 1WS = 5, etc.).
Bus Occupancy Calculations
32 bytes 7
4 because shared flags are not used + 2 byte CRC
n is the number of octets to transmit
abtc = assigned bits to channel
e.g. a channel with one time slot of 1 bit would require 8/1 = 8 time slots to
transmit a single octet.
8/abtc)
m
rc) + (5 + (1 + m)]
125 s
rc
32
tc
32
217
tc)}
(1 + 1/ba) sclk
1.1
(1 + 1/ba)
61 ns
NC
Application Notes
sclk
NC
4
PEB 20320
abtc
8
01.2000