Hardware Reference
In-Depth Information
141 mcp23017_write_both(DEFVAL,0x00); /
Clear default value
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142 mcp23017_write_both(OLAT,0x00); /
OLATx=0
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143 mcp23017_write_both(GPPU,0b11110000); /
4-7 are pull up
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144 mcp23017_write_both(IPOL,0b00000000); /
No inverted polarity
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4-7 inputs, 0-3 outputs
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145 mcp23017_write_both(IODIR,0b11110000);
146 mcp23017_write_both(INTCON,0b00000000); /
Cmp to previous
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147 mcp23017_write_both(GPINTEN,0b11110000); /
Int on changes
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148
149 /
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150
Loop until all interrupts are cleared:
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151
/
152 do {
153 int_flags = mcp23017_interrupts();
154 if ( int_flags != 0 ) {
155 v = mcp23017_captured();
156 printf(" Got change %04X values %04X\n",int_
flags,v);
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157 }
158 } while ( int_flags != 0x0000 && !is_signaled );
159 }
160
161 /
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162
Copy input bit settings to outputs :
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163
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164 static void
165 post_outputs(void) {
166 int inbits = mcp23017_inputs(); /
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Read inputs
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167 int outbits = inbits >> 4; /
Shift to output bits
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168 mcp23017_outputs(outbits); /
Copy inputs to outputs
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169 printf (" Outputs: %04X\n",outbits);
170 }
171
172 /
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173
Main program :
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174
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175 int
176 main(int argc,char
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argv) {
177 int int_flags, v;
178 int fd;
179
180 signal(SIGINT,sigint_handler); /
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Trap on SIGINT
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181
182 i2c_init(node); /
Initialize for I2C
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183 mcp23017_init(); /
Configure MCP23017 @ 20
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184
185 fd = gpio_open_edge(gpio_inta); /
Configure INTA pin
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186
