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release sensor input lecture
commit 4bb0e454363a70200d673f290dc349cf8c77eb39 Author: Julie Zelenski <[email protected]> Date: Mon Nov 18 00:18:49 2024 -0800 release sensor input lecture
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‎_data/unreleased.csv‎

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"/lectures/Guest/","Guest",false
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"/lectures/InfoSession/","Course Info Session",false
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"/lectures/OOP/","Object-oriented programming",false
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"/lectures/Sensors/","Sensors",false
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"/lectures/Sensors2/","Sensors output",false
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"/lectures/Wrap/","Wrap or There and Back Again",false

‎lectures/Sensors/README.md‎

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---
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released: true
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permalink: /lectures/Sensors/
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title: Sensor Input
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readings: |
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+ Wikipedia entry [analog-to-digital conversion](https://en.wikipedia.org/wiki/Analog-to-digital_converter)
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+ Readings for [i2c](/readings/i2c.pdf) and [spi](/readings/spi.pdf) protocols, sample driver code in `$CS107E`
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+ An excellent reference book for exploring sensors is "Make: Encyclopedia of Electronic Components Volume 3: Sensors" by Charles Platt and Fredrik Jansson. You can access the online version via Stanford Libraries Safari Books portal <https://searchworks.stanford.edu/view/13211489>.
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---

‎lectures/Sensors/code/accel-i2c/Makefile‎

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NAME = accel_demo
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EXTRAS = $(CS107E)/extras/d1_peripherals
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ARCH = -march=rv64im -mabi=lp64
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ASFLAGS = $(ARCH)
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CFLAGS = $(ARCH) -g -Og -I$$CS107E/include -I$(EXTRAS) -Wall -ffreestanding
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LDFLAGS = -nostdlib -L$$CS107E/lib -T memmap.ld
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LDLIBS = -lmango -lmango_gcc
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# vpath to find source files for d1 peripheral modules in extras
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# if no such file in build directory
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vpath %.c $(EXTRAS)
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all : $(NAME).bin
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%.bin: %.elf
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riscv64-unknown-elf-objcopy $< -O binary $@
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%.elf: %.o i2c.o
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riscv64-unknown-elf-gcc $(LDFLAGS) $^ $(LDLIBS) -o $@
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%.o: %.c
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riscv64-unknown-elf-gcc $(CFLAGS) -c $< -o $@
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%.o: %.s
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riscv64-unknown-elf-as $(ASFLAGS) $< -o $@
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run: $(NAME).bin
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mango-run $<
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clean:
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rm -f *.o *.bin *.elf *.list *~
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.PHONY: all clean run
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.PRECIOUS: %.elf %.o
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‎lectures/Sensors/code/accel-i2c/README.md‎

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Gy-521 3-axis accelerometer+gyroscope i2c sensor
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https://componentslibrary.com/gy-521-datasheet.html
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https://protosupplies.com/product/mpu-6050-gy-521-3-axis-accel-gryo-sensor-module/
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Uses i2c driver

‎lectures/Sensors/code/accel-i2c/accel_demo.c‎

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/*
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* Gy-521 3-axis accelerometer+gyroscope i2c sensor
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* Sample code below shows raw accel readings, no calibration/correction
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*
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* https://componentslibrary.com/gy-521-datasheet.html
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* https://protosupplies.com/product/mpu-6050-gy-521-3-axis-accel-gryo-sensor-module/
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*/
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#include "assert.h"
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#include "i2c.h"
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#include "printf.h"
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#include "timer.h"
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#include "uart.h"
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typedef struct {
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short x, y, z; // expressed in mg
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} axes_t;
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enum gy521_register {
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GY_WHO_AM_I = 0x75,
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CONFIG_ACCEL = 0x1C,
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READINGS_ACCEL = 0x3B,
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PWR_MGMT_1 = 0x6B,
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};
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static i2c_device_t *gy521_init(void) {
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uint8_t addr = 0x68; // confirm device addr with datasheet, components can differ!
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i2c_device_t *dev = i2c_new(addr);
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const uint8_t EXPECTED = addr; // expect device addr
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assert(i2c_read_reg(dev, GY_WHO_AM_I) == EXPECTED);
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i2c_write_reg(dev, PWR_MGMT_1, 0); // wake from sleep
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i2c_write_reg(dev, CONFIG_ACCEL, 0); // config accel for range -+2g, scale factor 16384
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return dev;
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}
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short extract_reading(uint8_t *bytes) {
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short scale_factor = 16384; // 16384 is 1g (1g == 1000mg)
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short reading = ((int8_t)bytes[0] << 8) + bytes[1];
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return (1000 * reading)/scale_factor;
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}
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void gy521_read(i2c_device_t *dev, axes_t *p) {
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uint8_t bytes[6]; // accel readings: x/y/z 2-byte big-endian
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i2c_read_reg_n(dev, READINGS_ACCEL, bytes, sizeof(bytes));
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p->x = extract_reading(&bytes[0]);
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p->y = extract_reading(&bytes[2]);
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p->z = extract_reading(&bytes[4]);
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}
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void main(void) {
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uart_init();
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i2c_init();
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i2c_device_t *gy = gy521_init();
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while (1) {
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axes_t a;
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gy521_read(gy, &a);
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printf("Reading x= %5dmg, y= %5dmg, z= %5dmg)\n", a.x, a.y, a.z);
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timer_delay(1);
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}
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}

‎lectures/Sensors/code/accel-i2c/doc/LSM6DS33-AN4682.pdf‎

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‎lectures/Sensors/code/accel-i2c/doc/LSM6DS33.pdf‎

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‎lectures/Sensors/code/adc-mcp3008-spi/Makefile‎

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NAME = adc_demo
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EXTRAS = $(CS107E)/extras/d1_peripherals
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ARCH = -march=rv64im -mabi=lp64
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ASFLAGS = $(ARCH)
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CFLAGS = $(ARCH) -g -Og -I$$CS107E/include -I$(EXTRAS) -Wall -ffreestanding
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LDFLAGS = -nostdlib -L$$CS107E/lib -T memmap.ld
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LDLIBS = -lmango -lmango_gcc
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# vpath to find source files for d1 peripheral modules in extras
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# if no such file in build directory
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vpath %.c $(EXTRAS)
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all : $(NAME).bin
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%.bin: %.elf
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riscv64-unknown-elf-objcopy $< -O binary $@
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%.elf: %.o spi.o mcp3008.o
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riscv64-unknown-elf-gcc $(LDFLAGS) $^ $(LDLIBS) -o $@
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%.o: %.c
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riscv64-unknown-elf-gcc $(CFLAGS) -c $< -o $@
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%.o: %.s
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riscv64-unknown-elf-as $(ASFLAGS) $< -o $@
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run: $(NAME).bin
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mango-run $<
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clean:
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rm -f *.o *.bin *.elf *.list *~
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.PHONY: all clean run
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.PRECIOUS: %.elf %.o

‎lectures/Sensors/code/adc-mcp3008-spi/README.md‎

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The MCP3008 is a 8-channel 10-bit analog to digital converter (ADC).
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It is set up to read the x,y coordinates from an analog joystick.
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See
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- https://learn.adafruit.com/raspberry-pi-analog-to-digital-converters/mcp3008
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- http://blog.falafel.com/mcp3008-analog-to-digital-conversion
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Wire the MCP3008 to the Pi as follows:
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MCP3008 VDD to Pi 3.3V
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MCP3008 VREF to Pi 3.3V
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MCP3008 AGND to Pi GND
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MCP3008 DGND to Pi GND
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MCP3008 CLK to Pi SCLK
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MCP3008 DOUT to Pi MISO
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MCP3008 DIN to Pi MOSI
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MCP3008 CS/SHDN to Pi CS
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doc/ contains
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- datasheet
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- circuit diagram
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- spi protocol
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‎lectures/Sensors/code/adc-mcp3008-spi/adc_demo.c‎

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/* File: adc_demo.c
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* ---------------
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* SPI + MCP3008 adc test
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*
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* Breadboard configured for analog inputs:
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* 2-axis joystick channels 0/1
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* Photoresistor channel 6
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* Force sensor channel 7
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*/
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#include "assert.h"
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#include "uart.h"
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#include "mcp3008.h"
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#include "printf.h"
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#include "strings.h"
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#include "timer.h"
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static const int MAX_VALUE = 1024;
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#define STRINGIFY_IMPL(x) #x
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#define AS_STRING(x) STRINGIFY_IMPL(x)
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#define ANSI_ESC(n) "\e[" AS_STRING(n) "m"
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#define RED ANSI_ESC(41)
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#define GREEN ANSI_ESC(42)
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#define YELLOW ANSI_ESC(43)
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#define BLUE ANSI_ESC(44)
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#define MAGENTA ANSI_ESC(45)
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#define CYAN ANSI_ESC(46)
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#define WHITE ANSI_ESC(47)
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#define NORMAL ANSI_ESC(0)
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static void print_analog_scale(int val, const char *label, const char *color) {
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assert(val <= MAX_VALUE);
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int quanta = 30;
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int on_quantized = val/quanta;
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int off_quantized = MAX_VALUE/quanta - on_quantized;
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char buf_on[on_quantized+1];
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char buf_off[off_quantized+1];
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memset(buf_off, ' ', sizeof(buf_off));
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memset(buf_on, '-', sizeof(buf_on));
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buf_on[sizeof(buf_on)-1] = '\0';
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buf_off[sizeof(buf_off)-1] = '\0';
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printf("%12s [%s%s%s%s]", label, color, buf_on, NORMAL, buf_off);
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}
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static void print_dashboard(int vert, int horiz, int light, int force){
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printf("\f\n mcp3008 Readings \n\n");
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print_analog_scale(vert, "Joy vert", CYAN);
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print_analog_scale(horiz, "Joy horiz", GREEN);
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printf("\n\n");
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print_analog_scale(light, "Light:", WHITE);
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printf("\n\n");
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print_analog_scale(force, "Force:", RED);
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}
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void main(void) {
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gpio_init();
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uart_init();
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mcp3008_init();
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printf("Starting program %s\n\n", __FILE__);
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while (1) {
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int vert = mcp3008_read(0);
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int horiz = mcp3008_read(1);
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int light = mcp3008_read(6);
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int force = mcp3008_read(7);
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print_dashboard(vert, horiz, light, force);
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timer_delay_ms(100);
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}
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}

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