Subject: Autostar Proc Traps... the List Sent: Saturday, April 15, 2000 21:09:07 From: firstname.lastname@example.org (richard seymour) Here are the numbered Proc Traps you should never see when using your Autostar. If you get one, there's been a hardware or computer error... Autostar versions before 2.0 -could- get Proc Trap 5 (IRQ), but v2.0 and later now handle that gracefully. What a Proc Trap is: an interrupt. The Motorola 68HC11 which is the heart (well, brain) of the Autostar can be optionally diverted from its normal path of operation by various hardware signals. (and a couple of software ones). These can arrive at any time, and the disruption of normal flow is called an Interrupt. The Autostar firmware program uses some of them (clock ticks to keep track of the time of day, Reset to start thing rolling at power-up, etc.) The ones it is -not- using (nor expecting) all cause a message to appear on the display, and then the Autostar will "freeze". Since it's a hardware problem, Meade expects us to turn it off, wait a few seconds, and then turn it back on. With luck, the cause will have been truly weird, and should not reappear. The message you'll see is: Proc. Trap N, with "N" being a hexadecimal number. The numbers mean: 0 Clock Monitor Fail 1 COP timeout failure 2 Illegal Op Code 3 Software Interrupt 4 XIRQ pin 5 IRQ pin 6,7,8 Timer Input Capture 1,2,3 9,A,B,C Timer Output Compare 1,2,3,4 D Combined TIC4/TOC5 E Pulse Accumulator Overflow F Pulse Acc Input Edge 10 SPI serial transfer complete Of the above list, numbers 2 and 3 cannot be blocked (or "masked"). If their circumstances occur, you'll Trap. In the months i've been reading Mike's site, i've seen reports of number 2 the most...even i've experienced it doing "point at Polaris, do lots of tiny speed-zero motions". It's what you'd get if the computer accidently tried to "execute" a byte which was really a data word. I suspect cold weather could cause a mis-fetch of an instruction which would cause it, too. The Number 5 used to occur (before they programmed around it) probably due to electrical noise getting picked up by one of the 68hc11's pins. "IRQ" is Interrupt ReQuest"... the 68hc11 has two pins you can wire external signals to which may want to request (or demand) service. The COP failure is a system the Autostar doesn't use: you can program a timer in the 68hc11 to kick that one if the processor stops doing -anything- else for up to a second. The Clock Monitor triggers if the system clock (the 8 megahertz crystal in the Autostar's case) slows down too far. The Timer Inputs and Timer Outputs are for monitoring the collection of timers, and some input and output pins, available inside the 68hc11. The Pulse Accumulator interrupts are for additional timer-like functions... you can tell a portion of the 68hc11 chip to count up how many times (yet) another pin is signalled from the outside, and to interrupt normal flow when a pre-set limit is reached, or if the counter merely rolls over (overflows) from full-scale to zero. The SPI is a secondary serial communication channel (independent of the rs232 channel) the 68hc11 can use to communicate with other devices. The Autostar does not appear to use it. Full details of all of the above are contained in the 590-page Motorola 68HC11 Reference Guide, available as a pdf file. (i'm sorry, i don't have the URL here... start at www.motorola.com, or use a search engine) May you never need the above information. --dick
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