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mookster1
Regular Member
Joined: 10/06/2011
Location: New ZealandPosts: 81 |
| Posted: 02:05am 26 Aug 2011 |
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Hi all,
I finally (!) had my Maximite sent out after ordering it, and in the several months since the original article was published I have had one or two big ideas I'd be willing to try out. The main one is an external bus system for the Maximite akin to what PCs have. I know the 20 I/O pins weren't originally intended for this, but I was thinking of designing and building an 8-bit bus using 8 of the 10 5V pins for the actual data transfer, and one 5V line to act as an interrupt for all the cards on the bus to alert them to new data that could possibly be addressed to them. (The address line goes low when the address data is sent, alerting the cards on the bus to read the address and decide if the data is intended for them or not.) When a line is not in use it is held high, so the cards can detect if there's an issue (i.e. if a card loses a connection with one pin) and do things accordingly. Could this system work reliably without having a clock line? If I was to have one it would probably be the I2C clock's SCL line. Beside each slot I was thinking of having a connector that connects to an analogue pin on the Maximite, that connects to each card via a separate connection to the actual bus. I don't know if anyone on here has undertaken a similar task, but any assistance would be appreciated  Edited by mookster1 2011-08-27
Capacitance is futile - roll on 2012! |
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haiqu
Senior Member
Joined: 30/07/2011
Location: AustraliaPosts: 152 |
| Posted: 08:07am 26 Aug 2011 |
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I did consider this idea, but the total lack of older 8-bit ISA cards on the secondhand market these days precluded further research. You already have modern bus standards like I2C and SPI built in, they're a much better option.
The world went serial.
unzip, strip, touch, finger, grep, mount, fsck, more, yes, fsck, fsck, fsck, umount, sleep |
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mookster1
Regular Member
Joined: 10/06/2011
Location: New ZealandPosts: 81 |
| Posted: 01:20am 27 Aug 2011 |
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Cheers haiqu, I thought I might have been an ugly duckling in considering this idea I was going to implement the I2C features as well as have a parallel-style bus. I'll probably implement RS232 serial comms when that feature is written into the firmware (I don't know a word of C and I don't have a PicKit3 to put my custom firmware onto the PIC32.)
Capacitance is futile - roll on 2012! |
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haiqu
Senior Member
Joined: 30/07/2011
Location: AustraliaPosts: 152 |
| Posted: 06:51pm 27 Aug 2011 |
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Such ideas have some merit, but the current hardware design of the Maximite isn't right for it anyhow. Better to use the Master Port for that.
It's never too late to learn another language. Lack of a PicKit3 isn't such a biggie, there are clones on eBay for $25.00 or so.
Rob
unzip, strip, touch, finger, grep, mount, fsck, more, yes, fsck, fsck, fsck, umount, sleep |
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