IA186EM/IA188EM
Data Sheet
8-Bit/16-Bit Microcontrollers
February 25, 2011
end of the timer interrupt routine being serviced, set the Interrupt Enable Bit in the Process
Status Word to globally disable interrupts prior to clearing the timer interrupt being serviced and
unmask the appropriate timer interrupts.
Errata No. 2
Problem: Lock up just after reset is released.
Description: Usually the first instruction is a long jump to the start of the user’s code. In this
case, the compiler apparently inserted a short jump instruction with zero displacement before the
expected long jump instruction. The OEM device stuttered, but recovered to execute the long
jump, while the device instruction pointer was corrupted, causing the lockup. In summary, a
short jump with zero displacement is a corner case that does not work in the device.
Workaround: Do not use a short jump instruction with zero displacement.
Errata No. 3
Problem: Intermittent startup.
Description: Processor either came out of reset normally, or would go into a series of watchdog
timeouts. The addition of 10K ohm pullups to the wr_n and rd_n outputs seemed to solve the
issue. Further analysis of the OEM device shows the presence of undocumented pullups on these
pins, which will pull them high when the reset condition tristates these pins. The device does not
include internal pullups on these pins allowing these outputs to float during reset.
Workaround: Add 10K ohm pullups to wr_n and rd_n pins to guarantee proper logic levels at
the end of reset.
Errata No. 4
Problem: Timer operation in continuous mode.
Description: The timers (Timer 0 and Timer 1) do not function per the specification when set in
continuous mode with no external timer input stimulus to initiate/continue count.
Workaround: None.
Errata No. 5
Problem: DMA interrupt will not bring device out of halt state.
®
IA211050831-19
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