s908ey16g2vfar Freescale Semiconductor, Inc, s908ey16g2vfar Datasheet - Page 159

• Manufacturer Part Number: s908ey16g2vfar
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

13.9 ESCI Arbiter
The ESCI module comprises an arbiter module designed to support software for communication tasks as
bus arbitration, baud rate recovery and break time detection. The arbiter module consists of an 9-bit
counter with 1-bit overflow and control logic. The CPU can control operation mode via the ESCI arbiter
control register (SCIACTL).
13.9.1 ESCI Arbiter Control Register
AM1 and AM0 — Arbiter Mode Select Bits
ALOST — Arbitration Lost Flag
Freescale Semiconductor
As shown in
AM1 and AM0.
This read-only bit indicates loss of arbitration. Clear ALOST by writing a 0 to AM1. Reset clears
ALOST.
(BUS OR 4 x BUS)
ESCI CLOCK
Address:
Reset:
Table
Read:
Write:
13-12, these read/write bits select the mode of the arbiter module. Reset clears
FRACTIONAL DIVIDE
Figure 13-19. ESCI Arbiter Control Register (SCIACTL)
$0018
PRESCALER — FD
÷1 OR 2 → 8.9687
AM1
Bit 7
(BYPASSED OR
Figure 13-18. ESCI Arbiter Counter Clock Selection
0
2 → 8
MC68HC908EY16A • MC68HC908EY8A Data Sheet, Rev. 1
Table 13-12. ESCI Arbiter Selectable Modes
31/32
AM[1:0]
= Unimplemented
ALOST
0 0
0 1
1 0
1 1
)
6
0
AM0
5
0
÷4
÷4
Idle / counter reset
Bit time measurement
Bus arbitration
Reserved / do not use
ACLK
4
0
PRESCALER — BPD
SCI BAUD RATE
÷1, 3, 4, or 13
ESCI Arbiter Mode
AFIN
3
0
ARUN
2
0
÷1, 2, 4, . . . 128
DIVIDER — BD
BAUD RATE
ACLK = 1
ACLK = 0
AROVFL
1
0
9-BIT ARBITER COUNTER
ARD8
Bit 0
ESCI Rx
0
÷16
ESCI Arbiter
f
f
Tx
Rx
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