IA186EM-PQF100I-R datasheet(132/133 Pages) INNOVASIC

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IA186EM/IA188EM

Data Sheet

8/16-BIT Microcontrollers

As of Production Version -03

which will pull them high when the reset condition tristates these pins. The Innovasic 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.

Version -03

1) Problem: There is a difference in how priority of timer interrupts are asserted between the original AMD part

and the Innovasic part.

Analysis: In the original AMD part, timer interrupts cannot be interrupted by another timer interrupt, even if the

new timer interrupt is of a higher priority. The Innovasic part will interrupt a timer interrupt with a higher

priority timer interrupt. Additionally, if a lower priority timer interrupt is interrupted with a higher priority timer

interrupt and another occurrence of the lower priority interrupt occurs during the processing of the higher

priority interrupt, upon execution of the EOI a new lower priority interrupt will be initiated, possibly orphaning

the original lower priority timer interrupt.

Workaround: When using nested interrupts, at the beginning of the interrupt routine before the global interrupts

are enabled with a CLI, timer interrupts must be specifically masked. At the end of the timer interrupt routine

being serviced, you need to 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.

2) Problem: Lock up just after reset is released.

Analysis: 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 IA

device instruction pointer was corrupted, causing the lock up. In summary, a short jump with zero

displacement is a corner case that does not work in the IA device.

Workaround: Do not use a short jump instruction with zero displacement.

3) Problem: Intermittent startup.

Analysis: 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 Innovasic 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.

3737 Princeton NE, Ste 130 • Albuquerque, NM 87107 • Tel 505.883.5263 • Fax 505.883.5477 • www.Innovasic.com

IA186EM-PQF100I-R датащи(PDF) 132 Page - InnovASIC, Inc