标签: canon

Inspired from Charlieb000 : http://icrontic.com/discussion/93568/reusing-card-reader-from-mp180-cannon-printer One of my friends had a Canon inkjet printer which was out of order. Due to the very high cost of inks, he decided not to repair it but to take the parts apart...   Fig. Disassembling the printer, plastics and metals would be dumped into recycle areas There was a card reader module which I thought it might be re-used. Fig. The card reader module, which used to read SD card, CF card, etc. (Edges of the PCB were already cut by me) Looking for information on the Internet, I found Charlieb000's post. In the post, the pins had been identified mostly so it made me more confident of modifying the module... A plastic case were drawn by Autodesk Inventor, and made by 3D printing. Fig. The case and cover drawn in Inventor Fig. The printed case and cover (I forgot to draw screw mounts, anyway the PCB could be fixed by heat glue) I did not like the 3mm green LED, so I would replace it. I found that there was already a transistor Q2 with resistor R31 for driving the LED, so I would desolder the LED and replace the resistor. Fig. The 3mm status LED, driving transistor Q2 and resistor R31. Fig. Basic components needed PCB: for mounting the AMS1117-3.3 regulator USB Cable: for connecting to PC LED and 100 Ohm resistor: replace signal LED 10uF Cap: decoupling cap for regulator Fig. The torn USB wire and cut PCB (only one small piece would be enough) Fig. Soldered wire for LED and components on PCB After soldering all the parts (according to the pin assignments from Charlieb000), I connected to the computer via a USB hub (Controller is GL850G), see my machine configuration below. Fig. My machine USB configuration To my surprise, the card reader could sometime be recognised, but sometimes could not... I guessed it was a 'startup' problem... Since from Charlieb000, the read cable had to be connected to 3.25V (or 3.3V), so it was guessed to be an 'Enable' or a 'reset' pin which was ACTIVE HIGH. Then a 10K resistor and a 10uF pull-down capacitor was connected. Afterwards, every time the card reader connected to the usb hub were successfully recognised However, when it is connected directly to the Intel's or TI's root hub, it could not be recognised... Nothing happened, sometimes a message box showing 'USB device not recognised' appeared. After struggling for some time, the terminating resistors, R1 and R2, were checked to be 100-Ohm. From my memory, usually USB signals were not terminated with such 'large' resistance. Hence, they were replaced by two 22-Ohm resistors. Fig. Resistors R1 and R2 were both changed to be 22-Ohm (I did not have such small resistors, so the outlook was not good) And... everything worked! The card reader could be detected when connected to any ports (Intel, TI's root hub or via GL850G) Below shows the schematic. Fig. Connection of card reader to PC Fig. The card reader was fixed into the case by heat glue and the case was sealed by strong instant glue. Fig. New USB card reader from old parts! Fig. USB Hub connected to a smart phone via OTG The white LED was so bright! I felt I was so lucky to have the problems solved... just by luck! 1. The reader could sometimes be recognised - solved by using a RC circuit to delay the startup 2. The reader could not recognised by some USB host controller - replaced the USB signal termination resistors Cheers.

Having product choice is good, there's not much question about that. When you can select from among a wide variety of products in a given category—whether at the supermarket, consumer-electronics vendor, or book source—you're likely to find something that you want, at a price you feel is OK, and the competition among products works to the consumer's benefit. But at the same time, it can become overwhelming. I recently was looking for a basic digital camera ($100 range) to replace a Canon Sureshot (8 Mpixels) which was operating erratically after several years of hard life. I decided to start with Canon again, since I assumed that their newer models would likely have a similar user interface, form factor, and functions as the one I had. I checked out the Canon site and was soon overwhelmed with the number of basic cameras and families they had. For some of them, their niche was obvious, such as ruggedized or water-resistant. But for others, I could not see the actual differences, except by a careful read-through of the product specifications. I soon felt like the fellow in the Max Ernst painting to the left, Man's head puzzled by the flight of a non-Euclidean fly . I don't mean to pick on Canon here. I found out that it's the same when you look for a GPS unit: so many families and so many products within each family, and that's just from a single vendor. Some are clearly targeted (such as for hikers or bikers) but still, an overwhelming set of choice remained. What I really needed from the vendors was a decision tree or selection flowchart, and most don't have that. I suppose somehow it makes sense to have so many models each with their own twist; I certainly don't understand the nuances of production and distribution in the consumer-product business. But you do have to wonder if the cost of having all the different production runs and sub-runs, bills of materials, labeling, packaging, documentation, order-entry set-up, and support wipes out whatever market and profit benefit there is to having so many similar products. We engineers would never do anything so foolish, right? Or maybe we would . Look at the product portfolio of any major analog IC vendor, for example, and you'll see an astonishingly wide and complex array of offerings for basic building blocks, such as op amps or converters. Yes, each one has its place and role, but still, it's a lot to look at and decide among. Some components, for example, are truly outstanding in one or two parameters, and are "merely" pretty good in others. In contrast, other offerings may not be especially outstanding in any one specification, but are very, very good in many of them. These are complex and subtle tradeoffs that the designer has to make when working the BOM when judging which one to use. Fortunately, most vendors offer selection guides to help you narrow down your choices, based on your needs and priorities. Do you find product proliferation in consumer end-products to be a problem? Has it ever caused you to just "give up" because you couldn't decide which model to get?