138 lines
3.8 KiB
C
138 lines
3.8 KiB
C
//
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// Gertboard Demo
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//
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// SPI (ADC/DAC) control code
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//
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// This code is part of the Gertboard test suite
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// These routines access the AD and DA chips
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//
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//
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// Copyright (C) Gert Jan van Loo & Myra VanInwegen 2012
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// No rights reserved
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// You may treat this program as if it was in the public domain
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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//
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// Try to strike a balance between keep code simple for
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// novice programmers but still have reasonable quality code
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//
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#include "gb_common.h"
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#include "gb_spi.h"
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// Set GPIO pins to the right mode
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// dad (digital-analogue-digital) GPIO mapping:
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// Function Mode
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// GPIO0= unused
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// GPIO1= unused
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// GPIO4= unused
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// GPIO7= SPI chip select B Alt. 0
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// GPIO8= SPI chip select A Alt. 0
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// GPIO9= SPI MISO Alt. 0
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// GPIO10= SPI MOSI Alt. 0
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// GPIO11= SPI CLK Alt. 0
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// GPIO14= unused
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// GPIO15= unused
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// GPIO17= unused
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// GPIO18= unused
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// GPIO21= unused
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// GPIO22= unused
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// GPIO23= unused
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// GPIO24= unused
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// GPIO25= unused
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//
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// For A to D and D to A we need the SPI bus and SPI chip selects A & B
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void setup_gpio()
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{
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INP_GPIO(7); SET_GPIO_ALT(7,0);
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INP_GPIO(8); SET_GPIO_ALT(8,0);
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INP_GPIO(9); SET_GPIO_ALT(9,0);
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INP_GPIO(10); SET_GPIO_ALT(10,0);
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INP_GPIO(11); SET_GPIO_ALT(11,0);
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} // setup_gpio
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//
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// Do digital to analogue to digital conversion
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//
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void main(void)
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{ int d, dac_val, v, s, i;
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printf ("These are the connections for the digital to analogue to digital test:\n");
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printf ("jumper connecting GP11 to SCLK\n");
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printf ("jumper connecting GP10 to MOSI\n");
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printf ("jumper connecting GP9 to MISO\n");
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printf ("jumper connecting GP8 to CSnA\n");
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printf ("jumper connecting GP7 to CSnB\n");
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printf ("jumper connecting DA1 on J29 to AD0 on J28\n");
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printf ("When ready hit enter.\n");
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(void) getchar();
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// Map the I/O sections
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setup_io();
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// activate SPI bus pins
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setup_gpio();
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// Setup SPI bus
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setup_spi();
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// The value returned by the A to D can jump around quite a bit, so
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// simply printing out the value isn't very useful. The bar graph
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// is better because this hides the noise in the signal.
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printf ("dig ana\n");
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for (d=0; d <= 256; d+= 32)
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{
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if (d == 256)
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dac_val = 255 * 16;
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else
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dac_val = d * 16;
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write_dac(1, dac_val);
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v= read_adc(0);
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// v should be in range 0-1023
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// map to 0-63
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s = v >> 4;
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printf("%3x %04d ", dac_val, v);
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// show horizontal bar
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for (i = 0; i < s; i++)
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putchar('#');
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for (i = 0; i < 64 - s; i++)
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putchar(' ');
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putchar('\n');
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short_wait();
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} // repeated write/read
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for (d=224; d >= 0; d-= 32)
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{
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dac_val = d * 16;
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write_dac(1, dac_val);
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v= read_adc(0);
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// v should be in range 0-1023
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// map to 0-63
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s = v >> 4;
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printf("%3x %04d ", dac_val, v);
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// show horizontal bar
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for (i = 0; i < s; i++)
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putchar('#');
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for (i = 0; i < 64 - s; i++)
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putchar(' ');
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putchar('\n');
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short_wait();
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} // repeated write/read
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printf("\n");
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restore_io();
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} // main
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