Z8F082A28100KIT ZILOG [Zilog, Inc.], Z8F082A28100KIT Datasheet - Page 169

• Manufacturer Part Number: Z8F082A28100KIT
• Description: Z8 Encore XP-R F08xA Series with eXtended Peripherals
• Manufacturer: ZILOG [Zilog, Inc.]

PS024705-0405
START
OCD Data Format
OCD Auto-Baud Detector/Generator
•
•
The OCD interface uses the asynchronous data format defined for RS-232. Each character
is transmitted as 1 Start bit, 8 data bits (least-significant bit first), and 1.5 Stop bits
(Figure 24)
To run over a range of baud rates (data bits per second) with various system clock frequen-
cies, the On-Chip Debugger contains an Auto-Baud Detector/Generator. After a reset, the
OCD is idle until it receives data. The OCD requires that the first character sent from the
host is the character
plus 7 data bits), framed between High bits. The Auto-Baud Detector measures this period
and sets the OCD Baud Rate Generator accordingly.
The Auto-Baud Detector/Generator is clocked by the system clock. The minimum baud
rate is the system clock frequency divided by 512. For optimal operation with asynchro-
nous datastreams, the maximum recommended baud rate is the system clock frequency
divided by 8. The maximum possible baud rate for asynchronous datastreams is the sys-
tem clock frequency divided by 4, but this theoretical maximum is possible only for low
noise designs with clean signals. Table 98 lists minimum and recommended maximum
baud rates for sample crystal frequencies.
D0
System Clock Frequency
0.032768 (32KHz)
Asserting the RESET pin Low to initiate a Reset.
Driving the DBG pin Low while the device is in STOP mode initiates a System Reset.
(MHz)
20.0
D1
1.0
80H
D2
Figure 24.OCD Data Format
. The character
Table 98. OCD Baud-Rate Limits
Maximum Baud
P R E L I M I N A R Y
Recommended
Rate (Kbps)
D3
2500.0
125.0
4.096
80H
D4
has eight continuous bits Low (one Start bit
Standard PC Baud
Recommended
Rate (bps)
1,843,200
D5
115,200
2400
Z8 Encore! XP
D6
Product Specification
Minimum Baud
Rate (Kbps)
D7
®
On-Chip Debugger
39
F08xA Series
1.95
0.064
STOP
151