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我使用 Arduino 作为奴隶只是为了读取电池的电压。Arduino中的程序是C。计算机程序是用QB64编写的，它连接到USB com端口#3。从程序和 QB64 可以很好地使引脚 13 闪烁。但是当我要求电压时，我得到的只是 10 个空格，没有数据。以下 QB64 代码是我尝试阅读的。评论显示了一些结果：

CLS
ctr = 1 '                           Counts number times you press continue

again:
INPUT "Press any key to continue"; d$ ' Run program to receive voltage 
OPEN "Com3:9600,n,8,1,ds0,cs0,rs" FOR RANDOM AS #1
_DELAY .5 '                                      delay to let com settle
FIELD #1, 35 AS m$

'            ****  Form Message to send to External Device ****
Command = 2: pin = 4: argument = 0 '   Code to Get analog voltage reading
msg$ = STR$(Command) + "," + STR$(pin) + "," + STR$(argument) + "*"
PRINT "msg$ Sent= "; msg$, CHR$(13) '                     Show Message
LSET m$ = msg$
PUT #1, , m$ '                  Send message to the external device
_DELAY 1


'*****  C code in external device  *****
'External device responds to message & prints to Com3 buffer.
' if ( cmd == 2)//getanalog
'   {
'        int sensorValue = analogRead(pin);//
'        delay(10);
'        float voltage= sensorValue*(5.0/1023.0);
'        Serial.print("Voltage =");
'        Serial.print(voltage);
'        Serial.print(",");
'       Serial.print("*");
'      }

CLOSE #1

m$ = "": msg$ = "" '                            Wipe out old messages

OPEN "Com3:9600,n,8,1,ds0,cs0,rs" FOR RANDOM AS #1
_DELAY .5 '                                    Delay to let Com Port settle
FIELD #1, 50 AS m$

t1 = TIMER '                                     Start time for getdata

getdata:
bytes% = LOC(1) '                             Check receive buffer for data
IF bytes% = 0 THEN GOTO getdata 'After thousands of cycles it continues
PRINT "Bytes="; bytes '                           Bytes remain at 0
DO UNTIL EOF(1)
    GET #1, , m$ '                         First GET #1 returns EOF=-1
    PRINT "LEN(m$)= "; LEN(m$) '               Length of m$ = 10
    IF INSTR(m$, "*") > 0 THEN GOTO duh '    Never finds End of Message (*)
LOOP

IF bytes% = 0 THEN GOTO getdata
t2 = TIMER '                                         End time, Have data
DeltaT = t2 - t1 '                                   How long did it take?
GOTO stepover '               If arrived here w/o End of Message signal

duh:
PRINT "DUH instr= "; INSTR(m$, "*") '               Never hits this line
stepover:

tmp$ = "DeltaT= #.### Seconds Until LOC(1) > 0" '   Various times 
PRINT USING tmp$; DeltaT
PRINT "m$ Received= "; m$ + "&" '                 Prints 10 spaces No Data
PRINT "endofdata= "; endofdata '                endofdata=0, Never got "*"
PRINT "ctr= "; ctr, CHR$(13) '    Show number of times you pressed continue
CLOSE #1
ctr = ctr + 1
GOTO again

注释中还包括写入 com 端口的 Slave 程序。一些 QB64 代码行不是必需的，但作为调试尝试包含在内

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