Panasonic typewriter interface v2

Panasonic Typewriter Interface

https://github.com/xunker/panasonic_typewriter_interface

Print text using the Interface Port of your compatible Panasonic KX-R Daisywheel typewriter, KX-W word processor, RK-T "CupWheel" typewriter, or KX-WD55 daisywheel printer. Emulates the serial/RS-232 function of the KX-R60 (currently working), and RP-K100/RP-K105 (in development) interface adapters.

Use your 🏋️heavy🥌 and 🐢slow🐌 typewriter as a noisy, inconvenient, inflexible, single-page printer!

A complete video of the high low-speed daisywheel action can be found on the TouYubes.

Table of Contents

• Compatibility
• Typewriter Pinout
• Arduino Wiring
• Code
• Printerering (aka, how to use this)
• Serial Configuration Terminal
• Known Problems
• Theory of Operation
• TODO
• License

Compatibility

KX-R series with MiniDIN-8 port

Developed and tested with my KX-R435, and should be compatible with any other Panasonic typewriter with the round, 8-pin MiniDIN port.

KX-W series with DE-9 port

Untested, but should work with machines which have a DE-9 (DB-9) connector. Currently does not work, but is in active development. See rp-k10x_vs_kx-r60.md for research details.

Typewriter Pinout

See PINOUT.md for detailed information about the typewriter connector pinout.

Arduino Wiring

Although this is built around the Arduino Nano, any 5V board which uses the ATmega328 will also work. Any other 5V ATmega MCU should work as as well (such as the ATmega32U4in the Arduino Micro), and clones like the LGT8F328 (tested).

Non-ATmega/AVR boards may work, as long as they are compatible with the libraries used in this project (see "Required Libraries"), have enough pins, and run on 5V (or are 5V-tolerant). I have not tried any of this.

Adapter Board

There's an adapter board available to ease assembly, and to provide additional features.

Connecting Arduino to Typewriter without Adapter Board

Minimum required:

Optional "Mode" button:

Separate USB-to-Serial Adapter: You can use the built-in USB port as the Serial connection, but hardware flow control will not be available. To use hardware flow control you will need to connect up to an external USB to Serial adapter:

You can also connect some optional additional LEDs for debugging (or because they look neat when they blink):

Code

The included code will read data from the Serial device (usually USB Serial) and relay that to the typewriter in the correct format.

Required Libraries

The following libraries are required by default. They can either be installed manually or via the Arduino IDE:

• SerialCmd
• MemoryUsage
• AceButton

SerialCmd and MemoryUsage are only needed by the Serial Configuration Terminal (enabled default). AceButton is only needed if the "Mode" button is enabled (enabled by default).

Configure

NOTE: if you are using the included adapter board, you do not need to do any additional configuration. Simply connect your cable and adjust the "Cable Type" jumpers so they are both closest to whichever LED (D1 or D2) is lit up.

Edit panasonic_typewriter_interface.ino and change the following lines as appropriate:

#define ON_LINE_PIN A0 // Output, active LOW
#define STB_PIN     A2 // Output, active LOW
#define ACK_PIN     A3 // Input, active LOW
#define TXD_PIN     A1 // Output; HIGH = 1, LOW = 0

#define GO_PIN      A6 // trigger printing to begin when this is pulled low

#define MODE_PIN    A7 // trigger printing to begin when this is pulled low

/* RTS_PIN/CTS_PIN are only needed if `#define ENABLE_RTS_CTS` is uncommented */
#define RTS_PIN 12 // incoming from RTS, active low (for ENABLE_RTS_CTS)
#define CTS_PIN 11 // outgoing to CTS, active low   (for ENABLE_RTS_CTS)

CHECK WHAT KIND OF CABLE YOU HAVE, and remember that a Macintosh-style printer cable likely has several pins swapped.

Once you're done, upload it to your Arduino-compatible MCU.

There is also a "Demo Mode" that will just print text automatically and not wait for input over serial; enable that by uncommenting // #define TEST_MODE in panasonic_typewriter_interface.ino.

Extra LEDs (Optional, default)

By default, there are 4 addition LEDs broken out to show the status of each of the signal lines (in addition to the built-in LED).

#define ON_LINE_LED 8
#define STB_LED     6
#define ACK_LED     2
#define TXD_LED     3
#define LED_BUILTIN 13 // "Status" LED

These LEDs will reflect the state of each respective signal. Note, this is a logic state, not the electrical state. That means for active-low pins like ON_LINE, STB, and ACT, a low signal will turn on the appropriate LED.

However, if you do not require these additional LEDs you can comment-out the line #define ENABLE_MULTIPLE_LEDS, and then only the built-in LED will be used.

Printerering (aka, how to use this)

Once the code is uploaded and your Arduino is properly connected to your typewriter, turn on your typewriter and load paper as appropriate.

Set Typewriter to "On-Line Mode"

Then, you must get in to "On-Line Mode". The command varies from model to model, so consult the owners manual for more detail. In the case of the KX-R435, you enter On-Line Mode by holding down the CODE key and then pressing E; the LCD should now say "On-Line Mode". To exit On-Line mode, or to stop printing, press CODE+E again.

Set microcontroller to "RUN" Mode

Once in "On-Line Mode", you'll need to set your Arduino to "Run" mode. If you are using the included adapter board, you do this by switching the "RUN/HALT" switch to "RUN". If you are have wired your own microcontroller, you will connect pin A7 (or whatever pin you assigned to GO_PIN) to ground.

Once you switch to "RUN" mode, reset the microcontroller once to ensure it's now in the correct mode.

As long as that pin is grounded, sentences will keep being sent to the typewriter.

Send text - SLOWLY

Finally, open a serial connection to your MCU (using the built-in Serial Console in the Arduino IDE works well).

The default speed is 300 baud. Yes, you read correctly, 300 baud. Because it's a freakin' TYPEWRITER! It can barely keep up with 30 char/sec. If you want a laser printer, you know where to find one.

Out of the box, the Arduino toolchain only gives the atMega328 a 64 byte serial buffer, which can hold about 2 seconds of data at 300 baud. I'd actually like to set the default speed to 110 baud, but no operating systems have supported that speed for at least 30 years. Yes, not even Linux despite the lies that stty tells you.

Send some text! With luck, you'll see it appear in your paper! Eventually!

Serial Configuration Terminal

See SERIAL_CONFIG.md.

Known Problems

Can't keep up with 300 baud without hardware flow control

The default speed is 300 baud (see "Send text - SLOWLY" for reasons), and even that has problems unless you use hardware flow control (RTS/CTS) and text will start to be dropped in about 2 lines.

This is because of two things issues:

• the Arduino Serial buffer is only 64 bytes, on the ATmega328
• Even the fastest Panasonic Daisywheels can only print 15 characters/sec, which is only half the speed of 300 baud, and most models can only print 12 CPS

There are two solutions:

• Use hardware flow control
  • On USB, this requires use of a separate USB-to-Serial adapter because the IC included on Arduino Nano does not connect any lines besides TxD, RxD, and DTR
  • The current Adapter Board can use a separate USB-to-Serial adapter connected to J4, with CTS connexted to "TX1" and RTC connected to "RX1"
  • Future versions of the adapter board will include footprints for a separate USB-to-serial converter
• add a "character delay" when you send, greater than 30ms/character
  • CoolTerm can do this: Options->Transmit->Use Transmit Character Delay

Reboot required when switching from from HALT to RUN with Serial Console

If Serial Console support is compiled in (the default), a reboot (via reset button) is require when going from HALT mode to RUN mode.

Mode button doesn't do anything

The "Mode Button" is currently GN/DN (goes nowhere & does nothing).

Theory of Operation

See rp-k10x_vs_kx-r60.md for a detailed sequence diagram.

TODO

Need

Rough order of importance:

• Working emulation of RP-K100 and RP-K105 adapters
• Use .h files properly; move code out of those
• Finish V2 adapter board which will give RTS/CTS and RS-232 options
  • must get RP-K100 and RP-K105 workign first
• Get special/accented character conversion functioning
• Convert special characters like tab ("\t") to spaces, to prevent typewriter from going crazy if no tabs have been set
  • ability to set tab-to-space count in serial console

Want

In no particular order:

• DTR/DSR support, for compatibility with older hosts that didn't use RTS/CTS
  • Ex: Apple II, C64, TRS80, etc.
• Transceivers or driver/receiver pairs for typewriter connection, for buffering and for possible 3.3v operation
  • 3x active-low drivers
  • 1x active-low receiver
• Better serial buffering
  • Default 64 byte buffer doesn't even do 300 baud well
  • Implement a 1K ring buffer? We have the free SRAM
  • This is less of an issue with RTS/CTS support
• Support alt Serial on LGT8F328 with Rx/Tx pins 5 & 6
• Separate serial interface for debugging output on different pins, with different baud rate
  • Software serial, or SERIAL1 on 328PB or LGT8F328
• I2C display support
  • in software, alreadu have hardware support via Stemma connector
• Automatically insert correct line-breaks, depending on CPI switch setting
  • May not be needed or even supported
    • Windows' generic/text only printer automatically wraps at 80 characters
• Automatically pause printing to insert next sheet of paper, based on line-spacing switch setting
  • MODE button becomes "Continue" button
• mode button cycles through CPI/Line Space settings? Need display for this?

License

GNU GPL 3