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Diffstat (limited to 'python/examples/Adafruit_Python_DHT/source/Beaglebone_Black')
4 files changed, 361 insertions, 0 deletions
diff --git a/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_dht_read.c b/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_dht_read.c new file mode 100644 index 0000000..0fa2761 --- /dev/null +++ b/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_dht_read.c @@ -0,0 +1,154 @@ +// Copyright (c) 2014 Adafruit Industries +// Author: Tony DiCola + +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: + +// The above copyright notice and this permission notice shall be included in all +// copies or substantial portions of the Software. + +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +// SOFTWARE. +#include <stdlib.h> +#include <string.h> + +#include "bbb_dht_read.h" +#include "bbb_mmio.h" + +// This is the only processor specific magic value, the maximum amount of time to +// spin in a loop before bailing out and considering the read a timeout. This should +// be a high value, but if you're running on a much faster platform than a Raspberry +// Pi or Beaglebone Black then it might need to be increased. +#define DHT_MAXCOUNT 32000 + +// Number of bit pulses to expect from the DHT. Note that this is 41 because +// the first pulse is a constant 50 microsecond pulse, with 40 pulses to represent +// the data afterwards. +#define DHT_PULSES 41 + +int bbb_dht_read(int type, int gpio_base, int gpio_number, float* humidity, float* temperature) { + // Validate humidity and temperature arguments and set them to zero. + if (humidity == NULL || temperature == NULL) { + return DHT_ERROR_ARGUMENT; + } + *temperature = 0.0f; + *humidity = 0.0f; + + // Store the count that each DHT bit pulse is low and high. + // Make sure array is initialized to start at zero. + int pulseCounts[DHT_PULSES*2] = {0}; + + // Get GPIO pin and set it as an output. + gpio_t pin; + if (bbb_mmio_get_gpio(gpio_base, gpio_number, &pin) < 0) { + return DHT_ERROR_GPIO; + } + bbb_mmio_set_output(pin); + + // Bump up process priority and change scheduler to try to try to make process more 'real time'. + set_max_priority(); + + // Set pin high for ~500 milliseconds. + bbb_mmio_set_high(pin); + sleep_milliseconds(500); + + // The next calls are timing critical and care should be taken + // to ensure no unnecssary work is done below. + + // Set pin low for ~20 milliseconds. + bbb_mmio_set_low(pin); + busy_wait_milliseconds(20); + + // Set pin as input. + bbb_mmio_set_input(pin); + + // Wait for DHT to pull pin low. + uint32_t count = 0; + while (bbb_mmio_input(pin)) { + if (++count >= DHT_MAXCOUNT) { + // Timeout waiting for response. + set_default_priority(); + return DHT_ERROR_TIMEOUT; + } + } + + // Record pulse widths for the expected result bits. + for (int i=0; i < DHT_PULSES*2; i+=2) { + // Count how long pin is low and store in pulseCounts[i] + while (!bbb_mmio_input(pin)) { + if (++pulseCounts[i] >= DHT_MAXCOUNT) { + // Timeout waiting for response. + set_default_priority(); + return DHT_ERROR_TIMEOUT; + } + } + // Count how long pin is high and store in pulseCounts[i+1] + while (bbb_mmio_input(pin)) { + if (++pulseCounts[i+1] >= DHT_MAXCOUNT) { + // Timeout waiting for response. + set_default_priority(); + return DHT_ERROR_TIMEOUT; + } + } + } + + // Done with timing critical code, now interpret the results. + + // Drop back to normal priority. + set_default_priority(); + + // Compute the average low pulse width to use as a 50 microsecond reference threshold. + // Ignore the first two readings because they are a constant 80 microsecond pulse. + uint32_t threshold = 0; + for (int i=2; i < DHT_PULSES*2; i+=2) { + threshold += pulseCounts[i]; + } + threshold /= DHT_PULSES-1; + + // Interpret each high pulse as a 0 or 1 by comparing it to the 50us reference. + // If the count is less than 50us it must be a ~28us 0 pulse, and if it's higher + // then it must be a ~70us 1 pulse. + uint8_t data[5] = {0}; + for (int i=3; i < DHT_PULSES*2; i+=2) { + int index = (i-3)/16; + data[index] <<= 1; + if (pulseCounts[i] >= threshold) { + // One bit for long pulse. + data[index] |= 1; + } + // Else zero bit for short pulse. + } + + // Useful debug info: + //printf("Data: 0x%x 0x%x 0x%x 0x%x 0x%x\n", data[0], data[1], data[2], data[3], data[4]); + + // Verify checksum of received data. + if (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) { + if (type == DHT11) { + // Get humidity and temp for DHT11 sensor. + *humidity = (float)data[0]; + *temperature = (float)data[2]; + } + else if (type == DHT22) { + // Calculate humidity and temp for DHT22 sensor. + *humidity = (data[0] * 256 + data[1]) / 10.0f; + *temperature = ((data[2] & 0x7F) * 256 + data[3]) / 10.0f; + if (data[2] & 0x80) { + *temperature *= -1.0f; + } + } + return DHT_SUCCESS; + } + else { + return DHT_ERROR_CHECKSUM; + } +} diff --git a/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_dht_read.h b/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_dht_read.h new file mode 100644 index 0000000..949ad2c --- /dev/null +++ b/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_dht_read.h @@ -0,0 +1,33 @@ +// Copyright (c) 2014 Adafruit Industries +// Author: Tony DiCola + +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: + +// The above copyright notice and this permission notice shall be included in all +// copies or substantial portions of the Software. + +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +// SOFTWARE. +#ifndef BBB_DHT_READ_H +#define BBB_DHT_READ_H + +#include "../common_dht_read.h" + +// Read DHT sensor connected to GPIO bin GPIO<base>_<number>, for example P8_11 is GPIO1_13 with +// base = 1 and number = 13. Humidity and temperature will be returned in the provided parameters. +// If a successfull reading could be made a value of 0 (DHT_SUCCESS) will be returned. If there +// was an error reading the sensor a negative value will be returned. Some errors can be ignored +// and retried, specifically DHT_ERROR_TIMEOUT or DHT_ERROR_CHECKSUM. +int bbb_dht_read(int type, int gpio_base, int gpio_number, float* humidity, float* temperature); + +#endif diff --git a/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_mmio.c b/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_mmio.c new file mode 100644 index 0000000..fda1beb --- /dev/null +++ b/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_mmio.c @@ -0,0 +1,73 @@ +// Copyright (c) 2014 Adafruit Industries +// Author: Tony DiCola + +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: + +// The above copyright notice and this permission notice shall be included in all +// copies or substantial portions of the Software. + +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +// SOFTWARE. +#include <fcntl.h> +#include <stdlib.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <sys/types.h> + +#include "bbb_mmio.h" + +#define GPIO_LENGTH 4096 +#define GPIO0_ADDR 0x44E07000 +#define GPIO1_ADDR 0x4804C000 +#define GPIO2_ADDR 0x481AC000 +#define GPIO3_ADDR 0x481AF000 + +// Store mapping of GPIO base number to GPIO address. +static uint32_t gpio_addresses[4] = { GPIO0_ADDR, GPIO1_ADDR, GPIO2_ADDR, GPIO3_ADDR }; + +// Cache memory-mapped GPIO addresses. +static volatile uint32_t* gpio_base[4] = { NULL }; + +int bbb_mmio_get_gpio(int base, int number, gpio_t* gpio) { + // Validate input parameters. + if (gpio == NULL) { + return MMIO_ERROR_ARGUMENT; + } + if (base < 0 || base > 3) { + return MMIO_ERROR_ARGUMENT; + } + if (number < 0 || number > 31) { + return MMIO_ERROR_ARGUMENT; + } + // Map GPIO memory if its hasn't been mapped already. + if (gpio_base[base] == NULL) { + int fd = open("/dev/mem", O_RDWR | O_SYNC); + if (fd == -1) { + // Error opening /dev/mem. Probably not running as root. + return MMIO_ERROR_DEVMEM; + } + // Map GPIO memory to location in process space. + gpio_base[base] = (uint32_t*)mmap(NULL, GPIO_LENGTH, PROT_READ | PROT_WRITE, MAP_SHARED, fd, gpio_addresses[base]); + if (gpio_base[base] == MAP_FAILED) { + // Don't save the result if the memory mapping failed. + gpio_base[base] = NULL; + return MMIO_ERROR_MMAP; + } + } + // Initialize and set GPIO fields. + memset(gpio, 0, sizeof(gpio)); + gpio->base = gpio_base[base]; + gpio->number = number; + return MMIO_SUCCESS; +} diff --git a/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_mmio.h b/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_mmio.h new file mode 100644 index 0000000..b6d5faa --- /dev/null +++ b/python/examples/Adafruit_Python_DHT/source/Beaglebone_Black/bbb_mmio.h @@ -0,0 +1,101 @@ +// Copyright (c) 2014 Adafruit Industries +// Author: Tony DiCola + +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: + +// The above copyright notice and this permission notice shall be included in all +// copies or substantial portions of the Software. + +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +// SOFTWARE. + +// Simple fast memory-mapped GPIO library for the Beaglebone Black. +// Allows reading and writing GPIO at very high speeds, up to ~2.6mhz! + +/* + // Example usage: + + #include <stdio.h> + #include "bbb_mmio.h" + + int main(int argc, char* argv[]) { + // Get GPIO pin. + // See the giant table of of pins in the system reference manual for details + // on the base and number for a given GPIO: + // https://github.com/CircuitCo/BeagleBone-Black/blob/master/BBB_SRM.pdf?raw=true + // Section 7 Connectors, table 12 shows P8_11 maps to GPIO1_13, so 1 is the + // gpio base and 13 is the gpio number. + gpio_t p8_11; + if (bbb_mmio_get_gpio(1, 13, &p8_11) < 0) { + printf("Couldn't get requested GPIO pin!\n"); + return 1; + } + // Set pin as output. + bbb_mmio_set_output(p8_11); + // Toggle the pin high and low as fast as possible. + // This generates a signal at about 2.6mhz in my tests. + // Each pulse high/low is only about 200 nanoseconds long! + while (1) { + bbb_mmio_set_high(p8_11); + bbb_mmio_set_low(p8_11); + } + return 0; + } + +*/ + +#ifndef BBB_MMIO_H +#define BBB_MMIO_H + +#include <stdint.h> + +#define MMIO_SUCCESS 0 +#define MMIO_ERROR_ARGUMENT -1 +#define MMIO_ERROR_DEVMEM -2 +#define MMIO_ERROR_MMAP -3 + +#define MMIO_OE_ADDR 0x134 +#define MMIO_GPIO_DATAOUT 0x13C +#define MMIO_GPIO_DATAIN 0x138 +#define MMIO_GPIO_CLEARDATAOUT 0x190 +#define MMIO_GPIO_SETDATAOUT 0x194 + +// Define struct to represent a GPIO pin based on its base memory address and number. +typedef struct { + volatile uint32_t* base; + int number; +} gpio_t; + +int bbb_mmio_get_gpio(int base, int number, gpio_t* gpio); + +static inline void bbb_mmio_set_output(gpio_t gpio) { + gpio.base[MMIO_OE_ADDR/4] &= (0xFFFFFFFF ^ (1 << gpio.number)); +} + +static inline void bbb_mmio_set_input(gpio_t gpio) { + gpio.base[MMIO_OE_ADDR/4] |= (1 << gpio.number); +} + +static inline void bbb_mmio_set_high(gpio_t gpio) { + gpio.base[MMIO_GPIO_SETDATAOUT/4] = 1 << gpio.number; +} + +static inline void bbb_mmio_set_low(gpio_t gpio) { + gpio.base[MMIO_GPIO_CLEARDATAOUT/4] = 1 << gpio.number; +} + +static inline uint32_t bbb_mmio_input(gpio_t gpio) { + return gpio.base[MMIO_GPIO_DATAIN/4] & (1 << gpio.number); +} + +#endif |