1.項(xiàng)目介紹

不管是LED數(shù)碼管，還是段碼式LCD液晶顯示屏，在顯示上都是由各個段位組合顯示成我們想要的字符的。本項(xiàng)目中采用的是4位段碼式LCD顯示屏，每一位由A~G共7個段位組成，另外還有P1~P4共4個點(diǎn)段位。為了實(shí)現(xiàn)在顯示程序上的可移植性和通用性，本項(xiàng)目通過數(shù)據(jù)結(jié)構(gòu)的設(shè)計(jì)形式結(jié)合驅(qū)動LCD顯示芯片內(nèi)部RAM的操作方法，給出一種既適合LED數(shù)碼管，也適合段碼式LCD液晶顯示屏的程序設(shè)計(jì)方法。

2.開發(fā)環(huán)境

軟件開發(fā)環(huán)境：Keil MDK 5.25，HC32005_SDK

硬件設(shè)計(jì)軟件：立創(chuàng)EDA

3.硬件設(shè)計(jì)

3.1.原理圖設(shè)計(jì)

硬件設(shè)計(jì)上使用了華大的Cortex-M0+內(nèi)核的HC32F005C6PA作為主控芯片，整個系統(tǒng)電壓工作在3.3V~5V之間，簡單的電源設(shè)計(jì)和復(fù)位電路，使用內(nèi)部24MHz晶振，通用的SWD在線調(diào)試和下載接口，在硬件外圍電路上省了不少的空間。4個用戶自定義按鍵、2個串口全部引出，一個連接SP232芯片進(jìn)行RS-232通訊，另一個直接引出TTL作調(diào)試監(jiān)控用、還有一個4位的LCD段碼式液晶屏，使用TM1621驅(qū)動芯片，作為顯示接口。

3.2.PCB設(shè)計(jì)

3.3.焊接調(diào)試

3.4.華大MCU初次使用，調(diào)試體會

所有的芯片，我都喜歡從新建工程開始研究，華大的MCU也不例外，官方也給出了MCU開發(fā)工具用戶手冊，可以對照手冊一步一步的新建工程。但是讓我困惑的第一件事是我調(diào)用delay函數(shù)進(jìn)行GPIO口翻轉(zhuǎn)的實(shí)驗(yàn)與官網(wǎng)給的DEMO例程實(shí)際的效果不一樣，很明顯是我的代碼有問題，GPIO口通過示波器測出來的速度明顯快相當(dāng)多，因?yàn)榈谝淮斡茫媸菬o從下手，一步步的從startup_hc32f005.s文件分析起，后來看到system_hc32f005.c，發(fā)現(xiàn)KEIL創(chuàng)建自動生成的這兩個文件和官方的DEMO例程不一樣，也是因?yàn)閟ystem_hc32f005.c文件中的一些初始化和調(diào)用導(dǎo)致了我芯片啟動后時鐘配置不正確，導(dǎo)致了GPIO口翻轉(zhuǎn)過快的問題。后面也是因?yàn)檫@邊的兩個文件其它部分的不一致導(dǎo)致了串口異常的問題，所以個人建議是：如果你要自建工程，還是用官方DEMO中的startup_hc32f005.s、system_hc32f005.c和system_hc32f005.h這3個文件覆蓋KEIL自動生成的這幾個文件。第2個需要注意的地方就是如果你要使用定時器、串口功能模塊之前，一定要開啟相應(yīng)模塊對應(yīng)的時鐘，這個大家都清楚;但別忘了，華大的MCU還需要配置PCLK等一些初始化操作，具體一可以參考代碼board.c文件中的BSP_InitSysClock函數(shù)。第3個就是串口模式的選擇和波特率的設(shè)定，這個跟其它的MCU，比如說ST之類的，有點(diǎn)不太一樣，具體一可以把這一塊的用戶手冊看一下，有助于加深理解，我也是想當(dāng)然跳了不少坑……

當(dāng)然華大半導(dǎo)體作為國產(chǎn)芯片，個人感覺還是不錯的，通過這一個項(xiàng)目的前期調(diào)試，耐下心來，一兩天就能上手了;性價比也是相當(dāng)?shù)母?，值得推薦!

4.程序設(shè)計(jì)

4.1.TM1621驅(qū)動設(shè)計(jì)

TM1621芯片內(nèi)部帶有靜態(tài)顯示內(nèi)存(RAM)，RAM以32*4位格式存儲所顯示的數(shù)據(jù)。RAM的數(shù)據(jù)直接映像到LCD驅(qū)動器，也就是說可以通過修改RAM的數(shù)據(jù)內(nèi)容，來修改液晶屏顯示的內(nèi)容。對應(yīng)的COM和SEG所對應(yīng)的RAM映像圖可以參考TM1621的數(shù)據(jù)手冊。對于TM1621我們有4個基礎(chǔ)的主要函數(shù)，分別如下所述：

4.1.1.void TM1621_Write(uint16_t value, uint8_t length)，這是TM1621最底層的函數(shù)， 是將value這個數(shù)據(jù)的高length個bit位寫入到TM1621芯片內(nèi)部，例如：

TM1621_Write(0x8020/*0b 1000 0000 0010 0000*/, 0x0C); // SYS_EN，將0x8020這個數(shù)值的高12位寫入到TM1621芯片

4.1.2.void TM1621_UpdateRAM(void)，更新TM1621顯示RAM，將全局?jǐn)?shù)組暫存儲的RAM數(shù)據(jù)統(tǒng)一一次性的更新到TM1621芯片內(nèi)，使用的是TM1621的WRITE命令，命令概述詳見TM1621數(shù)據(jù)手冊。

4.1.3.void TM1621_ModifyRAM(uint8_t index, uint8_t bit, uint8_t flag)，修改TM1621顯示RAM，根據(jù)數(shù)據(jù)結(jié)構(gòu)及算法確認(rèn)修改的TM1621顯示RAM的下標(biāo)和位下標(biāo)，flag是置位和清除的操作標(biāo)志。統(tǒng)一修改完成后，需要調(diào)用TM1621_UpdateRAM函數(shù)更新TM1621的顯示RAM，更新液晶屏顯示。

4.1.4.void TM1621_Init(void)，TM1621芯片初始化配置操作，詳見程序設(shè)計(jì)說明。

4.2.顯示設(shè)計(jì)

4.2.1.定義顯示字符和段位的映射表，如下代碼給出了38個常用的顯示字符：

typedef struct

{

char ch; /*字符索引*/

uint8_t segment[8]; /*字符對應(yīng)的段編碼*/

} DIGITRON_STRUCT;

const DIGITRON_STRUCT DIGITRON_TABLE[38] =

{

{' ', {0, 0, 0, 0, 0, 0, 0, 0}},

{'0', {1, 1, 1, 1, 1, 1, 0, 0}},

{'1', {0, 1, 1, 0, 0, 0, 0, 0}},

{'2', {1, 1, 0, 1, 1, 0, 1, 0}},

{'3', {1, 1, 1, 1, 0, 0, 1, 0}},

{'4', {0, 1, 1, 0, 0, 1, 1, 0}},

{'5', {1, 0, 1, 1, 0, 1, 1, 0}},

{'6', {1, 0, 1, 1, 1, 1, 1, 0}},

{'7', {1, 1, 1, 0, 0, 0, 0, 0}},

{'8', {1, 1, 1, 1, 1, 1, 1, 0}},

{'9', {1, 1, 1, 1, 0, 1, 1, 0}},

{'A', {1, 1, 1, 0, 1, 1, 1, 0}},

{'b', {0, 0, 1, 1, 1, 1, 1, 0}},

{'c', {0, 0, 0, 1, 1, 0, 1, 0}},

{'C', {1, 0, 0, 1, 1, 1, 0, 0}},

{'d', {0, 1, 1, 1, 1, 0, 1, 0}},

{'E', {1, 0, 0, 1, 1, 1, 1, 0}},

{'F', {1, 0, 0, 0, 1, 1, 1, 0}},

{'g', {1, 1, 1, 1, 0, 1, 1, 0}},

{'H', {0, 1, 1, 0, 1, 1, 1, 0}},

{'h', {0, 0, 1, 0, 1, 1, 1, 0}},

{'i', {0, 0, 1, 0, 0, 0, 0, 0}},

{'I', {0, 0, 0, 0, 1, 1, 0, 0}},

{'J', {0, 1, 1, 1, 1, 0, 0, 0}},

{'l', {0, 0, 0, 0, 1, 1, 0, 0}},

{'L', {0, 0, 0, 1, 1, 1, 0, 0}},

{'n', {0, 0, 1, 0, 1, 0, 1, 0}},

{'o', {0, 0, 1, 1, 1, 0, 1, 0}},

{'O', {1, 1, 1, 1, 1, 1, 0, 0}},

{'P', {1, 1, 0, 0, 1, 1, 1, 0}},

{'q', {1, 1, 1, 0, 0, 1, 1, 0}},

{'r', {0, 0, 0, 0, 1, 0, 1, 0}},

{'S', {1, 0, 1, 1, 0, 1, 1, 0}},

{'t', {0, 0, 0, 1, 1, 1, 1, 0}},

{'u', {0, 0, 1, 1, 1, 0, 0, 0}},

{'U', {0, 1, 1, 1, 1, 1, 0, 0}},

{'y', {0, 1, 1, 1, 0, 1, 1, 0}},

{'-', {0, 0, 0, 0, 0, 0, 1, 0}},

};

4.2.2.定義段位的組成關(guān)系，如下給出了顯示一位字符所需要的一個段組合，這些定義可以參照段碼式LCD液晶屏的PIN引腳關(guān)系定義：

const char DISPLAY_DIGIT_TABLE[4][7][3] =

{

{"1A", "1B", "1C", "1D", "1E", "1F", "1G"},

{"2A", "2B", "2C", "2D", "2E", "2F", "2G"},

{"3A", "3B", "3C", "3D", "3E", "3F", "3G"},

{"4A", "4B", "4C", "4D", "4E", "4F", "4G"},

};

const char DISPLAY_POINT_TABLE[4][3] =

{

"P1", "P2", "P3", "P4"

};

直白了說，就是我要在第一位上顯示一個‘8’這個字符，那這個字符肯定是由"1A", "1B", "1C", "1D", "1E", "1F", "1G"這7個段位組合顯示而成的。

4.2.3.定義段碼式LCD液晶屏PIN引腳關(guān)系與TM1621驅(qū)動芯片顯示RAM的對應(yīng)關(guān)系表，如下代碼所示：

const char LCD_CS_TABLE[4][32][3] =

{

{"1F","1A","2F","2A","3F","3A","4F","4A"," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "},

{"1G","1B","2G","2B","3G","3B","4G","4B"," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "},

{"1E","1C","2E","2C","3E","3C","4E","4C"," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "},

{"P1","1D","P2","2D","P3","3D","P4","4D"," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "," "},

};

這個數(shù)組的每一行對應(yīng)著一個COM，每一列對應(yīng)著一個SEG，這樣一個數(shù)據(jù)就直接映射成TM1621顯示RAM中的每一個BIT位;但需要注意的是，這個數(shù)據(jù)是需要根據(jù)原理圖的COM和SEG引腳的設(shè)計(jì)而定的;本項(xiàng)目在硬件設(shè)計(jì)上段碼式LCD液晶的COM0~COM3分別對應(yīng)的也是TM1621驅(qū)動芯片的COM0~COM3，所以在行的對應(yīng)關(guān)系上與段碼式LCD液晶屏PIN引腳關(guān)系保持一致，如果順序不一致，那在數(shù)組的行順序要也要做相應(yīng)的對應(yīng)排序;SEG段的數(shù)組對應(yīng)關(guān)系設(shè)計(jì)和COM段的思想是一樣的。

4.2.4.void DISPLAY_SearchCS(const char *str, uint8_t *com, uint8_t *seg)，這是最關(guān)鍵的一個函數(shù)，結(jié)合硬件電路設(shè)計(jì)，查找某個顯示字符對應(yīng)的每一個段編碼在TM1621顯示RAM的下標(biāo)和位下標(biāo)。

4.2.5.void DISPLAY_Digit(uint8_t index, char ch, uint8_t blink, uint8_t flag)，這是位顯示函數(shù)，index是位下標(biāo)，ch是需要顯示字符，blink是閃爍標(biāo)志，flag是刷新標(biāo)志;通過這個函數(shù)，我們可以調(diào)用DISPLAY_Digit(0, '8', 0, 1);在第一個位置上顯一個不閃爍的8字。

5.程序移植性和通用性

在相同硬件驅(qū)動的情況下，對應(yīng)不同設(shè)計(jì)的段碼式LCD，我們只需要根據(jù)段碼式LCD液晶屏PIN引腳關(guān)系，再結(jié)合硬件原理圖電路設(shè)計(jì)，修改LCD_CS_TABLE數(shù)組即可實(shí)現(xiàn)如上顯示功能。

有人說，我驅(qū)動LED數(shù)碼寫沒有用驅(qū)動芯片，那怎么辦呢?只是用了一個74HC595，或者是單片機(jī)引腳直接控制的，怎么辦呢?對于這種情況，我們的數(shù)據(jù)結(jié)構(gòu)和程序設(shè)計(jì)思想是一樣的，我們可以定義一個顯示緩存，在顯示的時候，將這個顯示緩存通過定時器的方式不斷的進(jìn)行刷新到LED數(shù)碼管，進(jìn)行顯示;當(dāng)然這邊不需要TM1621驅(qū)動程序了，應(yīng)該替換成驅(qū)動數(shù)碼管顯示的驅(qū)動程序。