Date: Dec 31, 2016
An alphanumeric input method on 4x4 keypads for Arduino. Stupid but works.
该程序展示了如何使用4x4矩阵键盘做到在两步之内输入92种字符。键盘可以是下图中的薄膜键盘或微动开关键盘，也适用于I2C键盘等。
It can input all 92 kinds of letters (lower and upper case), numbers and symbols within only 2 taps. Suitable for those who needs an input interface for his/her project but only has a small 4x4 keypad.
程序需要Arduino Keypad Library，由例程customKeypad修改得到。例程中推荐矩阵键盘接Arduino Uno的0-7引脚。应注意的是，这会占用Arduino的TX、RX引脚，进行串口通信的时候该引脚失效。
以下是可用的字符列表：
0 1 2 3 4 5 6 7 8 9
a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
@ $ % ! ( ) \ /
^ & ~ ? [ ] < *
: ; ` ' { } > -
# " . _ space +
A sample project Radio Freqency Text Transceiver (RFTT) is supplemented to show how this input method can be used in your Arduino projects.
| 1 | 2 | 3 | A |
| 4 | 5 | 6 | B |
| 7 | 8 | 9 | C |
| L | 0 | R | D |
Alphanumeric Keys:
For entering a number 0 - 9, tap the corresponding key twice.
Example:
'2' + '2' → 2
For entering a letter in lower case, tap the corresponding number, and tap A - D to select the letter. After selecting a number, function keys A - D becomes 1 - 4 for you to choose from the letters. The mapping follows the standard 12 key telephone keypad.
Example:
'3' + 'B' → e
For entering a letter in upper case, first tap function key B (Caps Lock), then do the same thing as above.
Example:
'B' + '3' + 'B' → E
Function Keys:
| Function Key | Function | Description |
|---|---|---|
| A | Backsapce | delete last symbol |
| B | Caps Lock | switch the case |
| C | Time Setting | time settings, used in RFTT. can define your own |
| D | Send | send button, used in RFTT. can define your own |
| L | Symbol Layout 1 | change to symbol layout 1. see below |
| R | Symbol Layout 2 | change to symbol layout 2. see below |
| @ | $ | % | ! |
| ^ | & | ~ | ? |
| : | ; | ` | ' |
| # | " |
We can enter the symbol layout 1 after 'L' is pressed. If any symbol is pressed, the symbol is keyed in and we then go back to the default layout.
Example:
'L' + 'B' → ?
'L' + '0' → #
| ( | ) | \ | / |
| [ | ] | < | * |
| { | } | > | - |
| . | _ | space | + |
In symbol layout 2 we can type in the space and dot right next to the key '0'.
Example:
'R' + 'B' → *
'R' + '0' → _
项目来自2016通信科协练习赛赛题。两个设备间使用nRF24L01射频模块实现字符串的收发和存储。项目使用EEPROM保存聊天记录，并在OLED上录入和显示消息。
由于要显示两个设备的聊天信息流，我们需要给消息加上时间戳。然而只有其中一个设备有RTC不掉电时钟模块，因此两个终端的行为不是对称的。有RTC的设备发消息时需要带上发送消息的时间，没有RTC的设备发消息时没有时间戳，此时另一端需要把时间戳返回过来。有RTC的一端还需要有设定时间的功能。
因此代码也分为有RTC的RFTT_RTC.ino和没有RTC的RFTT.ino。它们唯一的另一个区别是nRF24L01的TX、RX设置是相反的。
Wiring Arrangement:
| nRF24L01 | RTC | OLED | Keypad |
|---|---|---|---|
| CE = D9 | CE = D4 | SCL = A? | ROWS A0,A1,A2,A3 |
| CSN = D10 | IO = D3 | SDA = A? | COLS D8,D7,D6,D5 |
| MOSI = D11 | SCLK = D2 | ||
| MISO = D12 | |||
| SCK = D13 | |||
| IRQ = NC |
No Longer Maintenance:
The project is only for reference. It is not guaranteed for flawless compilation.