Z8F021ASH020SC datasheet(190/276 Pages) ZILOG

190 / 276 page

PS022815-0206

On-Chip Debugger

Z8 Encore! XP® 4K Series

Product Specification

171

If the OCD receives a Serial Break (nine or more continuous bits Low) the Auto-Baud

Detector/Generator resets. Reconfigure the Auto-Baud Detector/Generator by sending

80H

OCD Serial Errors

The On-Chip Debugger can detect any of the following error conditions on the DBG pin:

• Serial Break (a minimum of nine continuous bits Low)

• Framing Error (received Stop bit is Low)

• Transmit Collision (OCD and host simultaneous transmission detected by the OCD)

When the OCD detects one of these errors, it aborts any command currently in progress,

transmits a four character long Serial Break back to the host, and resets the Auto-Baud

Detector/Generator. A Framing Error or Transmit Collision may be caused by the host

sending a Serial Break to the OCD. Because of the open-drain nature of the interface,

returning a Serial Break break back to the host only extends the length of the Serial Break

if the host releases the Serial Break early.

The host transmits a Serial Break on the DBG pin when first connecting to the Z8 Encore!

XP® 4K Series devices or when recovering from an error. A Serial Break from the host

resets the Auto-Baud Generator/Detector but does not reset the OCD Control register. A

Serial Break leaves the device in DEBUG mode if that is the current mode. The OCD is

held in Reset until the end of the Serial Break when the DBG pin returns High. Because of

the open-drain nature of the DBG pin, the host can send a Serial Break to the OCD even if

the OCD is transmitting a character.

OCD Unlock Sequence (8-Pin Devices Only)

Because of pin-sharing on the 8-pin device, an unlock sequence must be performed to

access the DBG pin. If this squence is not completed during a system reset, then the PA0/

DBG pin functions only as a GPIO pin.

The following sequence unlocks the DBG pin:

1. Hold PA2/RESET Low.

1.0

125.0

115,200

1.95

0.032768 (32KHz)

4.096

2400

0.064

Table 108. OCD Baud-Rate Limits

System Clock Frequency

(MHz)

Recommended

Maximum Baud

Rate (Kbps)

Recommended

Standard PC Baud

Rate (bps)

Minimum Baud

Rate (Kbps)

Z8F021ASH020SC 数据表(PDF) 190 Page - Zilog, Inc.

Z8F021ASH020SC 数据表(HTML) 190 Page - Zilog, Inc.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载