AN2633 Freescale Semiconductor / Motorola, AN2633 Datasheet - Page 24

• Manufacturer Part Number: AN2633
• Description: LIN Drivers for SLIC Module on the MC68HC908QL4
• Manufacturer: Freescale Semiconductor / Motorola

AN2633/D
24
1. AN2503/D driver assumptions:
2. AN2575/D memory usage data comes from LIN08 driver manual for EY16.
MIN = external OSC, 9600 bps, no SLEEP mode, no parity check, no bit error checking
MAX = internal OSC, 19200 bps, SLEEP, parity checking, and bit error checking enabled
Each also has 7 messages defined, using 26 bytes of RAM
QY/QT bit-banged
AN2503/D
QY/QT bit-banged
AN2599/D
EY16 ESCI
AN2575/D
LINQL4-ASM
LINQL4-C
LINQL4-API
drivers
drivers
drivers
Version
(1)
(2)
Another key advantage to the SLIC is its ability to dramatically reduce the
number of required interrupts and the time spent in servicing those interrupts.
Table 9
of the SLIC and various other driver implementations. All have been normalized
to 3.2 MHz operation and 8-byte messages to accurately compare the relative
performance of each hardware and software combination.
In the QL4 MCU, the internal oscillator speed may be increased to 6.4 MHz by
setting the bus frequency select bit (BFS) in the oscillator status register
(OSCSTAT). This will further reduce the CPU loading by cutting ISR execution
times in half. This means that it is possible to reduce the average CPU usage
on the QL4 to below 0.1% and peak usage to 17 µs for an 8-byte LIN message
at 9615 bps.
LIN Drivers for SLIC Module on the MC68HC908QL4
Freescale Semiconductor, Inc.
API
Std
For More Information On This Product,
N
Y
Y
N
N
Y
Table 8. Driver Performance Metrics
shows a relative comparison of the CPU and interrupt loading impacts
Feature
Level
Go to: www.freescale.com
MAX
MIN
—
—
—
—
—
(+ 12 per 8 byte msg)
(+ 8 per 8 byte msg)
(+ 8 per 8 byte msg)
32 (+12 per 8 byte
24 (+ 8 per 8 byte
19 (+1 per 8 byte
RAM (Bytes)
msg)
msg)
msg)
18
32
11
Driver Code Resource Required
536 (+ 3 per msg)
836 (+ 3 per msg)
ROM (Bytes)
(driver + API)
1103 (driver)
838 (driver)
487 (API)
420 (API)
1130
172
120
MOTOROLA
(Bytes)
Stack
< 25
22
22
35
20
35
7