loading [Altus Metrum](https://altusmetrum.org) and other products that make
heavy use of 0402 passive components, and fine-pitch integrated circuits.
+## Challenges
+
+* The existing control computer will be replaced with a PC-compatible system
+ running [Debian GNU/Linux](https://debian.org) and
+ [OpenPnP](https://openpnp.org).
+
+* It appears that the stock board for doing things like sensing axis limits,
+ operating pneumatic actuators, etc, is actually attached to the control
+ computer using SCSI-1, and is based on an Intel 8031 with external EPROM.
+ Bdale hopes to reverse-engineer the protocol in use over this bus and use
+ a simple SCSI-1 interface on the control computer to interface with this
+ working board, so that it doesn't need to be replaced. This would also
+ allow us to leave almost all of the system wiring harness, all of which
+ is working, in place.
+
+* The existing analog servo amplifiers are fairly tightly coupled to the
+ control computer's electronics. Since the CSM84 came with some DC servo
+ control modules that take step and direction inputs and thus look can make
+ the axis servos look like stepper motors to the rest of the system, we're
+ going to try using a Smoothieboard and these modules to run the axis servos
+ using the existing power supplies.
+
+* The axis limit sensors currently feed into the main system I/O board, but
+ we'd like the Smoothieboard to be able to read them. This may require a
+ custom interface to extract those signals and feed them to the Smoothieboard
+ at appropriate interface voltages.
+
+* The existing vision system will be completely replaced by USB camera modules
+ attached to the new control computer.
+
+* The head-mounted vacuum sensor board will be replaced with something better
+ suited to OpenPnP's needs.
+
+* The reel feeders provided with the machine advance 8mm tapes by 4mm per
+ step, which is correct for parts that are of 0603 geometry and larger.
+ To feed 0402 parts, we either need to modify these feeders for a 2mm
+ advance, replace them with feeders that do 2mm advance per step, or just
+ throw away every other part on our 0402 reels.
+
## Sub-Projects
* The stock machine has a nozzle vacuum sensing board that uses an analog
signal. OpenPnP would rather have simple analog vacuum sensors on each
nozzle, readable by one of the system's control interfaces, then implement
the thresholds in software. That that end, Bdale designed a [replacement
- vacuum board](https://git.gag.com/hw/csm84vacuum) that uses 3 NXP 4115
- series analog output vacuum sensors, intended to be attached to three of
- the "thermistor" inputs on the Smoothieboard that also provides axis servo
- control.
+ vacuum board](https://git.gag.com/?p=hw/csm84vacuum;a=summary) that uses
+ 3 NXP 4115 series analog output vacuum sensors, intended to be attached to
+ three of the "thermistor" inputs on the Smoothieboard that also provides
+ axis servo control.
projects / web / gag.com / blobdiff