Hardware Reference
In-Depth Information
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41
Command line arguments are of the form <gpio>={low,high or none},
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42
for example : ./pull−up 7=high 8=low
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43
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44
Only the first character of the argument after '=' is checked.
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45
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46 int
47 main(int argc, char
argv) {
48 int x, gpio, p;
49 char arg [64];
50
51 gpio_init();
52
53 for ( x=1; x<argc; ++x ) {
54 if (sscanf(argv[x],"%d=%s",&gpio,arg)!=2)
55 goto errxit;
56 if (
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arg == 'n' )
57 p = −1;
58 else if (
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arg == ' l ' ||
arg == 'h ' )
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59 p =
arg == 'h ' ? 1 : 0;
60 else goto errxit;
61 if ( gpio < 0 || gpio > 31 ) {
62 fprintf(stderr,"%s : GPIO must be <= 31\n",
63 argv[x]) ;
64 return 1;
65 }
66 gpio_setpullup(gpio, p);
67 }
68 return 0;
69
70 errxit: fprintf(stderr,
"Argument '%s' must be in the form\n"
71 " <gpio>=<arg> where arg is h, l or n.\ n",
72 argv [ x ] ) ;
73 return 1;
74 }
75
76 /
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End pullup.c
/
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The default drive strengths after booting are listed next, along with the GPIO
addresses for the corresponding GPIO pads:
Address
GPIO Pads
Reset Drive Strength
0x2010002C
GPIO 0 to 27
8 mA
0x20100030
GPIO 28 to 45
16 mA
0x20100034
GPIO 46 to 53
8 mA
