After reading about them on Slashdot, I bought a picoLCD but got a bit frustrated trying to find some software to make it work.
What I really wanted was to be able to control it from Python, like this:
from picolcd import PicoLcd p = PicoLcd() p.clear() p.draw_text(0, 0, "Hello world")
or make a clock, like this:
from picolcd import PicoLcd
from datetime import datetime
import time
p = PicoLcd()
p.clear()
while True:
p.draw_text(3, 0, datetime.now().ctime()[:20])
time.sleep(0.5)
After a few attempts, it actually turned out to be very easy to control it via python-usb.
import usb
import time
def bytes(*b):
return "".join([chr(x) for x in b])
OUT_REPORT_LED_STATE = 0x81
OUT_REPORT_LCD_BACKLIGHT = 0x91
OUT_REPORT_LCD_CONTRAST = 0x92
OUT_REPORT_LCD_CONTROL = 0x93
OUT_REPORT_LCD_CLEAR = 0x94
OUT_REPORT_LCD_TEXT = 0x98
OUT_REPORT_LCD_FONT = 0x9C
class PicoLcd:
def __init__(self):
buses = usb.busses()
for bus in buses:
for device in bus.devices:
if device.idVendor == 0x04d8 and device.idProduct == 0xc001:
lcd = device
self.handle = lcd.open()
try:
self.handle.detachKernelDriver(0)
except usb.USBError:
pass
self.handle.claimInterface(0)
self.handle.setAltInterface(0)
def wr(self, m):
return self.handle.interruptWrite(usb.ENDPOINT_OUT + 1, m, 1000)
def draw_text(self, row, col, text):
addr = {0: 0x80, 1: 0xc0, 2:0x94, 3:0xd4}[row] + col
self.wr(bytes(0x94, 0x00, 0x01, 0x00, 0x64, addr))
self.wr(bytes(0x95, 0x01, 0x00, 0x01, len(text)) + text)
def clear(self):
for row in range(4):
self.draw_text(row, 0, " " * 20)
def backlight(self, brightness):
self.wr(bytes(OUT_REPORT_LCD_BACKLIGHT, brightness))
def leds(self, state):
self.wr(bytes(OUT_REPORT_LED_STATE, state))
def flash(self):
for brightness in range(20, 0, -1) + range(0, 21):
self.backlight(brightness)
time.sleep(.01)
if __name__ == "__main__":
from datetime import datetime
p = PicoLcd()
p.clear()
p.draw_text(0, 0, "It worked!")
p.draw_text(3, 0, datetime.now().ctime()[:20])
It seems to work fine on Linux (Ubuntu 9.04) and FreeBSD. I'll be extending the class to do more, including acting as an IR receiver.
Jan 2020 Update: I never did extend this code, but fortunately someone else has: the pypicolcd repository has the updated code, and also has a PyPI package. Details are in the README.md.