|
959
|
1 // ---------------------------------------------------------------------------
|
|
|
2 // Created/Adapted by Bill Perry 2012-03-16
|
|
|
3 // Copyright 2012 - Under creative commons license 3.0:
|
|
|
4 // Attribution-ShareAlike CC BY-SA
|
|
|
5 //
|
|
|
6 // This software is furnished "as is", without technical support, and with no
|
|
|
7 // warranty, express or implied, as to its usefulness for any purpose.
|
|
|
8 //
|
|
|
9 // @file LiquidCrystal_SR2W.h
|
|
|
10 // Connects a hd44780 LCD using 2 pins from the Arduino, via an 8-bit
|
|
|
11 // ShiftRegister (SR2W from now on).
|
|
|
12 //
|
|
|
13 // @brief
|
|
|
14 // This is the 2 wire shift register interface class for the LCD library
|
|
|
15 //
|
|
|
16 // The functionality provided by this class and its base class is a superset of
|
|
|
17 // the original functionality of the Arduino LiquidCrystal library and can
|
|
|
18 // be used as such.
|
|
|
19 // See the LCD class for a full description of the API functions available.
|
|
|
20 //
|
|
|
21 // It works with a 8-bit unlatched, no-tristate, unidirectional SIPO (Serial-In-Parallel-Out)
|
|
|
22 // shift register (IE a very simple SR), and an hd44780 LCD in 4-bit mode.
|
|
|
23 // Any such shift register should do (pref. 74LS family IC's for 2-wire).
|
|
|
24 // 74LS164 and 74HC595 have been exstensively tested.
|
|
|
25 //
|
|
|
26 //
|
|
|
27 // 2 Pins required from the Arduino:
|
|
|
28 // - Data/Enable
|
|
|
29 // - Clock
|
|
|
30 // The Data pin is also used to control the enable signal
|
|
|
31 // LCD RW-pin hardwired to LOW (only writing to LCD).
|
|
|
32 // Busy Flag (BF, data bit D7) is not read.
|
|
|
33 //
|
|
|
34 // Original project homepage: http://code.google.com/p/arduinoshiftreglcd/
|
|
|
35 //
|
|
|
36 // Shift register bits
|
|
|
37 // Bit #0 - (cannot be used on 74HC595)
|
|
|
38 // Bit #1 - optional backlight control
|
|
|
39 // Bit #2 - connects to RS (Register Select) on the LCD
|
|
|
40 // Bit #3 - connects to LCD data inputs D4
|
|
|
41 // Bit #4 - connects to LCD data inputs D5
|
|
|
42 // Bit #5 - connects to LCD data inputs D6
|
|
|
43 // Bit #6 - connects to LCD data inputs D7
|
|
|
44 // Bit #7 - enables the LCD enable-puls (via the diode-resistor AND "gate")
|
|
|
45 //
|
|
|
46 // Wiring for a 74LS164
|
|
|
47 // ---------------------
|
|
|
48 // 1k/4.7k
|
|
|
49 // +--------[ Resistor ]--------+---(LCD Enable)
|
|
|
50 // | |
|
|
|
51 // | 74LS164 (VCC) |
|
|
|
52 // | +----u----+ | _V_ diode
|
|
|
53 // (data pin)---+---+--1-|A VCC|-14-+ |
|
|
|
54 // | | | |
|
|
|
55 // +--2-|B Q7|-13------+
|
|
|
56 // 3-|Q0 Q6|-12--(LCD D7)
|
|
|
57 // (BL Circuit)--------4-|Q1 Q5|-11--(LCD D6)
|
|
|
58 // (LCD RS)------------5-|Q2 Q4|-10--(LCD D5)
|
|
|
59 // (LCD D4)------------6-|Q3 /MR|--9--(VCC)
|
|
|
60 // +-7-|GND CP|--8--(clock pin)
|
|
|
61 // | +---------+
|
|
|
62 // | 0.1uf
|
|
|
63 // (gnd)-----||----(vcc)
|
|
|
64 //
|
|
|
65 // Wiring for a 74HC595
|
|
|
66 // --------------------
|
|
|
67 // NOTE: the 74HC595 is a latching shift register. In order to get it to operate
|
|
|
68 // in a "non latching" mode, RCLK and SCLK are tied together. The side effect of this
|
|
|
69 // is that the latched output is one clock behind behind the internal shift register bits.
|
|
|
70 // To compensate for this the wiring is offset by one bit position lower.
|
|
|
71 // For example, while the backlight is hooked to Q0 it is still using bit 1 of
|
|
|
72 // of the shift register because the outputs are 1 clock behind the real internal shift
|
|
|
73 // register.
|
|
|
74 //
|
|
|
75 // 74HC595 (VCC)
|
|
|
76 // +----u----+ | +-----------------------(BL circuit)
|
|
|
77 // (LCD RS)------------1-|Q1 VCC|-16-+ | +--------------------(data pin)
|
|
|
78 // (LCD D4)------------2-|Q2 Q0|-15----+ | 1k/4.7k
|
|
|
79 // (LCD D5)------------3-|Q3 SER|-14-------+---[ Resistor ]--+--(LCD Enable)
|
|
|
80 // (LCD D6)------------4-|Q4 /OE|-13--(gnd) |
|
|
|
81 // (LCD D7)------------5-|Q5 RCLK|-12-------+ |
|
|
|
82 // | | | |
|
|
|
83 // +------6-|Q6 SCLK|-11-------+--(clock pin) |
|
|
|
84 // | 7-|Q7 /MR|-10--(VCC) |
|
|
|
85 // | +-8-|GND Q6'|--9 |
|
|
|
86 // | | +---------+ diode _V_
|
|
|
87 // | | 0.1uf |
|
|
|
88 // | (gnd)-----||----(vcc) |
|
|
|
89 // +-----------------------------------------------+
|
|
|
90 //
|
|
|
91 //
|
|
|
92 // Backlight Control circuit
|
|
|
93 // -------------------------
|
|
|
94 // Because the shift resiter is not latching the outputs, the backlight circuitry
|
|
|
95 // will "see" the output bits as they are shifted into the shift register which
|
|
|
96 // can cause the backlight to flicker rather than remain constantly on/off.
|
|
|
97 // The circuit below slows down the transitions to the transistor to remove
|
|
|
98 // the visible flicker. When the BL input is HIGH the LCD backlight will turn on.
|
|
|
99 //
|
|
|
100 // (value depends on LCD, 100ohm is usually safe)
|
|
|
101 // (LCD BL anode)---[ resistor ]---(vcc)
|
|
|
102 //
|
|
|
103 // (LCD BL cathode)-------------------------------+
|
|
|
104 // |
|
|
|
105 // D
|
|
|
106 // |
|
|
|
107 // (BL input)----[ 4.7k Resistor ]----+-------G-|-< (2N7000 FET)
|
|
|
108 // | |
|
|
|
109 // (0.1uf) = S
|
|
|
110 // | |
|
|
|
111 // (gnd) (gnd)
|
|
|
112 //
|
|
|
113 //
|
|
|
114 //
|
|
|
115 //
|
|
|
116 // History
|
|
|
117 // 2012.03.16 bperrybap - creation/adaption from SR header to create SR2W header.
|
|
|
118 // Fixed typo in SR2W mask define names
|
|
|
119 // @author B. Perry - bperrybap@opensource.billsworld.billandterrie.com
|
|
|
120 // --------------------------------------------------------------------------------
|
|
|
121 #ifndef _LIQUIDCRYSTAL_SR2W_
|
|
|
122 #define _LIQUIDCRYSTAL_SR2W_
|
|
|
123
|
|
|
124 #include <inttypes.h>
|
|
|
125 #include "LCD.h"
|
|
|
126 #include "FastIO.h"
|
|
|
127
|
|
|
128
|
|
|
129 // two-wire SR output bit constants
|
|
|
130 // ---------------------------------------------------------------------------
|
|
|
131
|
|
|
132 #define SR2W_BL_MASK 0x02
|
|
|
133 #define SR2W_RS_MASK 0x04
|
|
|
134 #define SR2W_DATA_MASK 0x78 // data bits are hard coded to be SR bits 6,5,4,3
|
|
|
135 #define SR2W_EN_MASK 0x80 // cannot ever be changed
|
|
|
136
|
|
|
137 class LiquidCrystal_SR2W : public LCD
|
|
|
138 {
|
|
|
139 public:
|
|
|
140 /*!
|
|
|
141 @method
|
|
|
142 @abstract LCD 2 wire SHIFT REGISTER constructor.
|
|
|
143 @discussion Defines the pin assignments that connect to the shift register.
|
|
|
144 The constructor does not initialize the LCD. Assuming 1 line 8 pixel high
|
|
|
145 font.
|
|
|
146
|
|
|
147 @param srdata[in] Arduino pin for shift register data line.
|
|
|
148 @param srclock[in] Arduino pin for shift register clock line.
|
|
|
149 @param blpol[in] optional backlight polarity (default = POSITIVE)
|
|
|
150 */
|
|
|
151 LiquidCrystal_SR2W (uint8_t srdata, uint8_t srclock, t_backlighPol blpol = POSITIVE);
|
|
|
152
|
|
|
153 /*!
|
|
|
154 @function
|
|
|
155 @abstract Send a particular value to the LCD.
|
|
|
156 @discussion Sends a particular value to the LCD for writing to the LCD or
|
|
|
157 as an LCD command using the shift register.
|
|
|
158
|
|
|
159 Users should never call this method.
|
|
|
160
|
|
|
161 @param value[in] Value to send to the LCD.
|
|
|
162 @param mode[in] DATA=8bit data, COMMAND=8bit cmd, FOUR_BITS=4bit cmd
|
|
|
163 the LCD.
|
|
|
164 */
|
|
|
165 virtual void send(uint8_t value, uint8_t mode);
|
|
|
166
|
|
|
167
|
|
|
168 /*!
|
|
|
169 @function
|
|
|
170 @abstract Switch-on/off the LCD backlight.
|
|
|
171 @discussion Switch-on/off the LCD backlight.
|
|
|
172 The setBacklightPin has to be called before setting the backlight for
|
|
|
173 this method to work. @see setBacklightPin.
|
|
|
174
|
|
|
175 @param mode[in] backlight mode (0 off, non-zero on)
|
|
|
176 */
|
|
|
177 void setBacklight ( uint8_t mode );
|
|
|
178
|
|
|
179 private:
|
|
|
180
|
|
|
181 /*!
|
|
|
182 @method
|
|
|
183 @abstract Initializes the LCD pin allocation
|
|
|
184 @discussion Initializes the LCD pin allocation and configuration.
|
|
|
185 */
|
|
|
186 void init ( uint8_t srdata, uint8_t srclock, t_backlighPol blpol, uint8_t lines, uint8_t font );
|
|
|
187
|
|
|
188 /*!
|
|
|
189 * @method
|
|
|
190 * @abstract takes care of shifting and the enable pulse
|
|
|
191 */
|
|
|
192 void loadSR (uint8_t val);
|
|
|
193
|
|
|
194 fio_register _srDataRegister; // Serial Data pin
|
|
|
195 fio_bit _srDataMask;
|
|
|
196 fio_register _srClockRegister; // Clock Pin
|
|
|
197 fio_bit _srClockMask;
|
|
|
198
|
|
|
199 uint8_t _blPolarity;
|
|
|
200 uint8_t _blMask;
|
|
|
201 };
|
|
|
202 #endif
|
