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Brother KH-930 Knitting Machine Hacking and Knitting Tutorial

A video tutorial that was already published 2010 by Becky Stern gives a great overview of the proces to work with a hacked brother knitting machine KH-930e. The hack is based on the work of Steve Conklin and published on github here: https://github.com/adafruit/knitting_machine

The Brother KH-930e Knitting Machine can be controlled by Open Source software. Parts of the process require commandline experience and Python knowledge.

Disk Drive/Computer Connection Notes

The external floppy drive for this machine was the same as a Tandy PDD1 (Portable Disk Drive 1). This drive is connected using a serial port. There is documentation on the internet about how to connect these drives to computers, but the connector pinout on the knitting machine is different than the drive, and I didn't find that documentation to be helpful. I was able to figure out the connector pinout by examining the knitting machine PCB.

Knitting Machine/Computer Connection Notes

The knitting machine drive connection uses CMOS voltage levels, not RS-232. Here is the pinout of the drive connector on the knitting machine:

      _____
      |   |
______|___|______
|   |   |   |   |
| 7 | 5 | 3 | 1 |
|___|___|___|___|
|   |   |   |   |
| 8 | 6 | 4 | 2 |
|___|___|___|___|

The pin numbering is shown as they are labeled on the knitting machine PCB, and does not agree with other documents I found on the web.

Connector Pinout
PinSignalI/ONotes
1Ground  
2 OutTied to 5, Pulled up through 1K resistor
3CTS?In(Tie to pin 2)
4No Connection  
5 OutTied to 2, Pulled up through 1K resistor
6RXDIn 
7TXDOut 
8RTS?OutFollows state of Pin 3 (buffered)

Methods of connecting the knitting machine to a computer

Using a FTDI serial adapter cable (RECOMMENDED)

Using an FTDI adapter is the best way to assure that you are interfacing with the machine using the same signal voltages as the original external floppy drives. This is documented on this wiki page, which will someday be merged with this one.MProg only runs under windows.

Using a USB serial adapter WITH flow control

This is a method I have used extensively with one model of knitting machine, but I no longer recommend it. Although it does not require any additional hardware like a FTDI adapter, this method does not present the exact same voltage levels to the knitting machine as the external drives which were designed to work with the machine. Although I have not had any reports of problems, it is possible that this method could stress the knitting machine input circuitry, and therefore I think it is safest not to use it.

Cable connections with flow control
Knitter9 pin connector
15
63
72
84

Using a USB serial adapter WITHOUT flow control

I have pulled pin 3 high, and am not using flow control in my software. I have not had problems with data loss while sending to the knitting machine, and the machine I am using is fast enough to always keep up with data received from the knitting machine. The data rate is 9600 bps, and the largest amount of data sent at once is 1024 bytes. Here is the cable I am using to connect the knitter with a USB 9 pin serial port:

Cable connections without flow control
Knitter9 pin connector
15
2 tie to 3 
63
72

Software Interface Information

There are a number of documents on the web about the Tandy PDD1 and the serial API for it, Most of them are incomplete. The knitter places the drive into a mode called "FDC emulation Mode", which allows access to raw sectors. This document is the most complete documentation I was able to find: Media:Tandy-Disk-Reference.pdf

External Disk Drive Emulator

I have written software that emulates the external disk. It runs under Linux and keeps the data as files on the linux file system. This allows knitting designs to be saved and restored using the emulation computer. I am using these files to reverse-engineer the knitting machine file format. The emulator is written in Python, and released under the GPL. It has been tested most extensively under Ubuntu Linux. I have reports that it does not work on windows due to problems with the serial library. It has been successfully run under OSX. If you have any information to add about platforms that it does or doesn't work on, let me know and I will update this informationI am happy to work with people who are trying to use the emulator with different models of knitting machine, and hoep to improve compatibility with other machines. The source code is available in the git repository listed above. Software for manipulating Brother data file: I have begun a python class which will provide an API to the brother data files. Source code is in the git repo. Knitting Machine File Format: A lot of the file format is now understood. Documentation is in the git repo.Work on this continues.This work was greatly helped by prior work performed by John R. Hogerhuis and posted on the kminternals yahoo group.

Links

Media:Portable_Disk_Drive_Operation_Manual.pdf

BL5 Brotherlink 5 serial or USB cable Brotherlink information

Yahoo group dedicated to hacking brother machines

Brother Liberation Front is working on open source interfaces

Info and protocols for the FB-100 interface

KE-100 motor drive (not sure that this is the right model drive for the KH-930E)

Adafruit Tutorial: https://learn.adafruit.com/electroknit?view=all

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