Grovepi+ LCD module with RGB Backlight 詳細研究

直接按照sample code去執行....大致上來說是可以執行...

他這個module 跟一般的LCD 16x2的模組不太一樣的是

有外接兩個控制IC......

這兩個控制IC分別為PCA9633 LED 4bit Fm+ led driver IC (背光控制) 和 AIP31068L (文字控制)


所以你只要拿兩根GPIO來當I2C 就可以控制它們....

GPIO2 -> SDA
GPIO3 -> SCL

然後啟動RPI內部的i2 hardware module 就可以控制lcd module....

先來看背光的部分 ....

首先來看一下sample code...

其中   DISPLAY_RGB_ADDR = 0x62

# set backlight to (R,G,B) (values from 0..255 for each)
	def setRGB(r,g,b):
	bus.write_byte_data(DISPLAY_RGB_ADDR,0,0)
	bus.write_byte_data(DISPLAY_RGB_ADDR,1,0)
	bus.write_byte_data(DISPLAY_RGB_ADDR,0x08,0xaa)
	bus.write_byte_data(DISPLAY_RGB_ADDR,4,r)
	bus.write_byte_data(DISPLAY_RGB_ADDR,3,g)
	bus.write_byte_data(DISPLAY_RGB_ADDR,2,b)

它定義了一個function..... setRGB(r,g,b)

裡面用I2C 傳輸了6個Byte......分別針對

address   data

0              0
1              0
8              0xaa
4              r_val
3              g_val
2              b_val

看了 code以後一定沒有甚麼感覺...因為你不曉得為什麼要這樣做....

所以我來看一下datasheet...

以8pin 的version 來看....

slave address 為  (0x62 <<1) | RW

剛好就是 這行 code定義的 ....

DISPLAY_RGB_ADDR = 0x62

以後換了其他的IC...先查datasheet...再可以一樣畫葫蘆

接下來看一下register summary

可以看到...

reg 0h  ->  Mode register 1
reg 1h ->  Mode register 2
reg 8h ->  LED output state register
reg 4h ->  brightness control LED2
reg 3h ->  brightness control LED1
reg 2h ->  brightness control LED0

接下來再看更詳細一點

sample code 是填 0  (bus.write_byte_data(DISPLAY_RGB_ADDR,0,0))

所以意思就是說....PCA9633 不需要去回應 

sample code 是填 0  (bus.write_byte_data(DISPLAY_RGB_ADDR,1,0))

output drivers not enabled.......4LED outputs 被 設定 open-drain 架構

output change on STOP...

這些都跟 I2C 的protocol 比較有關....

接下來再看來reg 0x8

sample code 是填 0  (bus.write_byte_data(DISPLAY_RGB_ADDR,0x8,0xaa))

0xaa ->1010 _1010   ....也就是   LDR 3 到LDR0 都是填  10b.....

意思就是   LED driver X(3,2,1,0) 都是用 PWMx register來控制

接下來看 reg 0x4...也就是PWM register

    不過這邊我看了datasheet...沒有看到他說....reg4h 就是R的value...不過這個好解決...

     try and error就知道....以上大概就是RGB backlight的控制方式.....

     直接從別人寫好的sample code去 逆向工程....真的比自己花時間去try快很多....

     前提是別人寫好的sample code會動歐....

 接下來看文字的部分 ....

sample code如下:

DISPLAY_TEXT_ADDR = 0x3e

def textCommand(cmd):
	bus.write_byte_data(DISPLAY_TEXT_ADDR,0x80,cmd)

def setText(text):
	textCommand(0x01) # clear display
	time.sleep(.05)
	textCommand(0x08 | 0x04) # display on, no cursor
	textCommand(0x28) # 2 lines
	time.sleep(.05)
	count = 0
	row = 0
	for c in text:
	if c == '\n' or count == 16:
	count = 0
	row += 1
	if row == 2:
	break
	textCommand(0xc0)
	if c == '\n':
	continue
	count += 1
	bus.write_byte_data(DISPLAY_TEXT_ADDR,0x40,ord(c))

 
 可以看出大概的流程是

  clear display ->  set display on, no cursor -> set 2 lines -> sleep....等待一段時間 ....

-> 然後用一個loop把你要傳的文字串拆解成一個一個的文字傳送...處理換行...

不過沒有搭配datasheet...也是不知其所以然....

接下來看看datasheet.....

可以看出來 address (0x3e<<1) | rw_bit    ->(DISPLAY_TEXT_ADDR = 0x3e)

然後control byte 會指定device 的register offset..可以看得出...他只有兩種選擇....

 0x80和  0xc0 ...就只差在 RS bit...從下圖的instruction set可以看的出來...

RS 為 '0' -> address 0x80
RS 為 '1' -> address 0xc0 (但是sample code的address為0x40...但應該沒有差)

datasheet上有給一個instruction 的流程圖

對照著 code看就很清楚...

textCommand(0x01) # clear display SCREEN CLEAR

textCommand(0x08 | 0x04) # display on, no cursor, CURSOR RETURN...

這就是DISPLAY SWITCH.....把(D,C,B) 設成 (1,0,0)

D : Display on/off      -> on
C : cursor on/off        -> off
B : blink on/off          -> off

textCommand(0x28) # 2 lines

這就是function set .... 8 -> D3  -> 2R

接下來看

bus.write_byte_data(DISPLAY_TEXT_ADDR,0x40,ord(c))

其實就是在寫  data write (0x40 -> RS 為 '1')

這邊他呼叫了一個function  ord()

查了一下google....

內建函數(function) ord() ，回傳字元參數(parameter) c 的Unicode 編碼值

要把你的字元轉換成 Unicode的編碼值....然後才可以傳送進去

Reference : 背光datasheet
Reference : 文字datasheet

GrovePi+ Lession 1 -> LED

買了GrovePi+  先來玩LED吧....

但一開始看到包裝...LED的兩隻腳都一樣長...死定了...這樣我怎麼判斷那個是正極

只好問問google大神

從中間的圖可以看出那個是正..那個是負....

從說明書的說明來看... 先安裝Grovepi的套件　

git clone https://github.com/DexterInd/GrovePi.git

cd GrovePi/Script

改變權限讓install.sh可以被執行

sudo chmod +x install.sh

執行這個script

sudo ./install.sh

她大概就是幫你把一些要裝得套件裝一裝....像是

 按照第一個sample.... 

grove_led_blink.py...

===================================================

#!/usr/bin/env python
	# GrovePi LED blink Example for the Grove LED Socket (http://www.seeedstudio.com/wiki/Grove_-_LED_Socket_Kit)
	#
	# The GrovePi connects the Raspberry Pi and Grove sensors. You can learn more about GrovePi here: http://www.dexterindustries.com/GrovePi
	#
	# Have a question about this example? Ask on the forums here: http://www.dexterindustries.com/forum/?forum=grovepi
	#
	'''
	## License
	The MIT License (MIT)
	GrovePi for the Raspberry Pi: an open source platform for connecting Grove Sensors to the Raspberry Pi.
	Copyright (C) 2015 Dexter Industries
	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:
	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.
	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	THE SOFTWARE.
	'''
	import time
	from grovepi import *
	# Connect the Grove LED to digital port D4
	led = 4
	pinMode(led,"OUTPUT")
	time.sleep(1)
	print "This example will blink a Grove LED connected to the GrovePi+ on the port labeled D4. If you're having trouble seeing the LED blink, be sure to check the LED connection and the port number. You may also try reversing the direction of the LED on the sensor."
	print " "
	print "Connect the LED to the port labele D4!"
	while True:
	try:
	#Blink the LED
	digitalWrite(led,1) # Send HIGH to switch on LED
	print "LED ON!"
	time.sleep(1)
	digitalWrite(led,0) # Send LOW to switch off LED
	print "LED OFF!"
	time.sleep(1)
	except KeyboardInterrupt: # Turn LED off before stopping
	digitalWrite(led,0)
	break
	except IOError: # Print "Error" if communication error encountered
	print ("Error")

==================================================
不過一執行就遇到問題...

ImportError: No module named grovepi

每當我有問題的時候...就找找google大神並且try and error...

有人回文說

go to  /home/pi/Desktop/Grovepi/Software/python/ and run 
sudo python setup.py install
再執行一次就可以work...你就會看到LED on off  on off....

程式裡面的 led = 4 就是用 shield 的D4

如果你用D3....記得把code 改成 led = 3....