140 lines
5.7 KiB
Plaintext
140 lines
5.7 KiB
Plaintext
<sect1 id="picolcd">
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<title>The Mini-Box USB LCD (picoLCD 20x2) Driver (picolcd)</title>
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<para>
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This section covers the installation and use of the Mini-Box USB LCD (picoLCD
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20x2) display.
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</para>
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<para>
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The picoLCD page indicates that the device can be connected via I2C or USART.
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This lcdproc driver, however, is limited to the USB connected model.
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</para>
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<sect2 id="picolcd-setup">
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<title>Setting up the picoLCD</title>
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<para>
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The picoLCD device as used by this driver is USB connected and may be purchased
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with an internal USB header connector (5-pin to 5-pin) or an external cable
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(Type-A to 5-pin). See: http://www.mini-box.com/picoLCD-20x2-OEM. It may also
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come pre-installed on systems like the Mini-Box M300:
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http://www.mini-box.com/Mini-Box-M300-LCD.
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</para>
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<para>
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Using the USB LCD with this driver requires the usblcd library from Mini-box.com
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(avaiable at http://www.mini-box.com/picoLCD-20x2-OEM). The usblcd library
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requires libusb and libhcd. Your distribution may or may not already provide
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these libraries. The only kernel driver required is the USB host controller
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driver (uhci_hcd on the M300) required to fire up the usb bus to which the LCD is
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attached.
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</para>
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<para>
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Lastly, the usbfs file system must be mounted on /proc/bus/usb.
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<code>mount -t usbfs usbfs /proc/bus/usb</code>
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</para>
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<para>
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Once connected and with libusblcd, libusb and libhid installed, testing the USB LCD
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can be done with the "usblcd" program that comes with the usblcd library. You can
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also change the USB LCD's initial display (what it shows when you initialize the
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device) by using the usblcd binary's "splash" command.
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</para>
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<para>
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To use the picolcd with lcdproc, add picolcd to the lcdproc configure drivers option
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(or use all) and then start LCDd with the "-d picolcd" option. The driver has
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sane default options and the options that are user configurable are limited to mostly
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simple items, like contrast and which keys to lights up.
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</para>
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</sect2>
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<sect2 id="picolcd-options">
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<para>
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Contrast: 0-1000. 0 is visible, and 1000 is not on my M300. Default is 0.
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</para>
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<para>
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Keylights: 0/1. 0 turns off the key LEDs and 1 turns them on. Default is 1.
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</para>
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</sect2>
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<sect2>
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<para>
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Key0Light: if Keylights is set to 1, you can disable the directional pad LED by
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setting this value to 0. Default is 1.
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</para>
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</sect2>
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<sect2>
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<para>
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Key1Light: if Keylights is set to 1, you can disable the F1 LED by setting this value
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to 0. Default is 1.
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</para>
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</sect2>
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<sect2>
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<para>
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Key2Light: if Keylights is set to 1, you can disable the F2 LED by setting this value
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to 0. Default is 1.
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</para>
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</sect2>
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<sect2>
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<para>
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Key3Light: if Keylights is set to 1, you can disable the F3 LED by setting this value
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to 0. Default is 1.
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</para>
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</sect2>
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<sect2>
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<para>
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Key4Light: if Keylights is set to 1, you can disable the F4 LED by setting this value
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to 0. Default is 1.
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</para>
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</sect2>
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<sect2>
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<para>
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Key5Light: if Keylights is set to 1, you can disable the F5 LED by setting this value
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to 0. Default is 1.
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</para>
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</sect2>
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<sect2>
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<para>
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KeyTimeout: (Advanced) This value controls how long LCDd waits for a key press when
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get_key is called. The value represents microseconds and the default is 500 or .5
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seconds. Lowering this value will make LCDd more responsive but also causes LCDd to use
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more CPU time and, as the timeout grows shorter, key presses become harder to detect.
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Larger values make key presses more reliable if somewhat slow to take effect.
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</para>
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</sect2>
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<sect2 id="picolcd-status">
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<title>picolcd driver status</title>
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<para>
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The lcdproc picolcd driver relies upon Mini-Box's usblcd library to setup the USB/HID
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interface. Unfortunately the usblcd library is very thin and tends to put function
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results on stdout/stderr instead of in return values. They (Mini-Box) really had
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scripting interfaces in mind.
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</para>
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<para>
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The primary example of this is that I had to write a replacement (get_key_events) for
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usblcd's read_events so that I could get the key presses back to the calling function
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instead of on stdout. usblcd also has a large number of function shells for which no
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code exists yet. I am not an expert on HID and USB coding, but if and as time permits
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and hardware is available I will try and improve this drivers access to the hardware in
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order to get back data (get_contrast for example) and to potentially drive multiple
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pcioLCDs at once (or pick the one we want out of many).
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</para>
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<para>
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To sum up, this driver right now stabs and hopes since response data is lacking.
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</para>
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<para>
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The hardware also reports key-up events. Normally this would be of no issue (they are
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usually a 0 or 'no key') except that when keys are used in combonation, the key-up
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event may actually come back as multiple events depending on how the user released the
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keys. If the key-up event for a multiple key press comes back as two events, the first
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up event will actually look like a new key press. The algorithm in get_key tries to
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deal with this in a sane way and toss out all key-up events for now. The hardware is
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touchy and both combo key-down and key-up actions may be reported as mutiple events if
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the user is more than a tenth of a second (maybe less?) off in motions.
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</para>
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</sect2>
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<sect2 id="picolcd-copy">
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<title>Copyright</title>
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<para>
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The lcdproc picolcd driver was written by Gatewood Green (woody@nitrosecurity.com)
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or (woody@linif.org) and paid for by NitroSecurity, Inc (nitrosecurity.com).
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</para>
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</sect2>
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</sect1>
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