IA8044 Datasheet, PDF (48/49 Pages) InnovASIC, Inc – SDLC COMMUNICATIONS CONTROLLER

IA8044/IA8344
SDLC COMMUNICATIONS CONTROLLER
Data Sheet
ISSUE:
Port2 buffer bits set high are not actively driven when executing a MOVX A,@Ri or
a MOVX @Ri,A instruction. During these instructions any bit that was driven low
by the previous value on Port2 but is high in the Port2 buffer will not reach a valid
high level before ALE goes low.
SOLUTION: Avoid the use of these instructions or add strong pullups (approximately 10K) to
Port2 externally.
ISSUE:
Race condition on transmit response in AUTO mode causes bad control byte to be
transmitted..
SOLUTION: In firmware wait for RTS=1 before telling transmit to start.
ISSUE:
Device does not sense the end of buffer during a receive.
SOLUTION: No workaround available.
ISSUE:
Receiving continuous flags (7Eh) while in loop mode will not allow a slave device to
transmit. The device is only able to transmit when the line is idle.
SOLUTION: Do not send continuous flags.
Version 00/P01:
ISSUE:
The following registers change value after an external reset, STAD, TBS, TBL, TCB,
RBS, RBL, RFL, and RCB. These registers should retain there pre-reset values.
SOLUTION: Store register values in memory (internal or external) to be restored after reset.
ISSUE:
Device may miss external interrupts with narrow pulse widths when in edge sensitive
mode and tight software loops that check TCON.
SOLUTION: Place NOPs in loop to allow time to capture interrupt..
ISSUE:
Intermittent drop out in slave mode, followed by normal operation. Dropouts can
be caused by either noise on the reset pin or XTAL1 being unconnected when using
a clock source.
SOLUTION: Filter reset if necessary. Ensure that XTAL1 is tied low when using a clock source.
ISSUE:
When used as a slave in loop mode the device may misinterpret a byte due to an
internal bit counter error. This may cause the device to think it has seen a go-ahead
and can transmit when it actually should not transmit.
SOLUTION: No workaround available.
ISSUE:
If the synchronous mode is used (external SCLK is provided), gating off the SCLK
may cause the device to communicate erratically. Depending on when the SCLK is
gated off the SIU may not have finished its present task. When the SCLK is
restarted the device may not respond to communications.
SOLUTION: Do not gate off the external SCLK.
Copyright © 2003
innovASIC
The End of Obsolescence™
ENG210010112-00
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