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<H1><A NAME="section_1">32 LISTING OF hello.c</A></H1>
<pre class="vhdl">
1 #include "stdint.h"
2 #include "avr/io.h"
3 #include "avr/pgmspace.h"
4
5 #undef F_CPU
6 #define F_CPU 25000000UL
7 #include "util/delay.h"
8
9
10 //----------------------------------------------------------------------//
11 // //
12 // print char cc on UART. //
13 // return number of chars printed (i.e. 1). //
14 // //
15 //----------------------------------------------------------------------//
16 uint8_t
17 uart_putc(uint8_t cc)
18 {
19 while ((UCSRA & (1 << UDRE)) == 0) ;
20 UDR = cc;
21 return 1;
22 }
23
24 //----------------------------------------------------------------------//
25 // //
26 // print char cc on 7 segment display. //
27 // return number of chars printed (i.e. 1). //
28 // //
29 //----------------------------------------------------------------------//
30 // The segments of the display are encoded like this:
31 //
32 //
33 // segment PORT B
34 // name Bit number
35 // ----A---- ----0----
36 // | | | |
37 // F B 5 1
38 // | | | |
39 // ----G---- ----6----
40 // | | | |
41 // E C 4 2
42 // | | | |
43 // ----D---- ----3----
44 //
45 //-----------------------------------------------------------------------------
46
47 #define SEG7(G, F, E, D, C, B, A) (~(G<<6|F<<5|E<<4|D<<3|C<<2|B<<1|A))
48
49 uint8_t
50 seg7_putc(uint8_t cc)
51 {
52 uint16_t t;
53
54 switch(cc)
55 { // G F E D C B A
56 case ' ': PORTB = SEG7(0,0,0,0,0,0,0); break;
57 case 'E': PORTB = SEG7(1,1,1,1,0,0,1); break;
58 case 'H': PORTB = SEG7(1,1,1,0,1,1,0); break;
59 case 'L': PORTB = SEG7(0,1,1,1,0,0,0); break;
60 case 'O': PORTB = SEG7(0,1,1,1,1,1,1); break;
61 default: PORTB = SEG7(1,0,0,1,0,0,1); break;
62 }
63
64 // wait 800 + 200 ms. This can be quite boring in simulations,
65 // so we wait only if DIP switch 6 is closed.
66 //
67 if (!(PINB & 0x20)) for (t = 0; t < 800; ++t) _delay_ms(1);
68 PORTB = SEG7(0,0,0,0,0,0,0);
69 if (!(PINB & 0x20)) for (t = 0; t < 200; ++t) _delay_ms(1);
70
71 return 1;
72 }
73
74 //----------------------------------------------------------------------//
75 // //
76 // print string s on UART. //
77 // return number of chars printed. //
78 // //
79 //----------------------------------------------------------------------//
80 uint16_t
81 uart_puts(const char * s)
82 {
83 const char * from = s;
84 uint8_t cc;
85 while ((cc = pgm_read_byte(s++))) uart_putc(cc);
86 return s - from - 1;
87 }
88
89 //----------------------------------------------------------------------//
90 // //
91 // print string s on 7 segment display. //
92 // return number of chars printed. //
93 // //
94 //----------------------------------------------------------------------//
95 uint16_t
96 seg7_puts(const char * s)
97 {
98 const char * from = s;
99 uint8_t cc;
100 while ((cc = pgm_read_byte(s++))) seg7_putc(cc);
101 return s - from - 1;
102 }
103
104 //-----------------------------------------------------------------------------
105 int
106 main(int argc, char * argv[])
107 {
108 for (;;)
109 {
110 if (PINB & 0x40) // DIP switch 7 open.
111 {
112 // print 'Hello world' on UART.
113 uart_puts(PSTR("Hello, World!\r\n"));
114 }
115 else // DIP switch 7 closed.
116 {
117 // print 'HELLO' on 7-segment display
118 seg7_puts(PSTR("HELLO "));
119 }
120 }
121 }
122 //-----------------------------------------------------------------------------
<pre class="filename">
app/hello.c
</pre></pre>
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