Content from time import ticks_ms, sleep from math import log, ceil, floor from bme680.bme680 import BME680_I2C from mch22 import exit_python from machine import SoftI2C, Pin import display import buttons bme = BME680_I2C(SoftI2C(scl=Pin(21), sda=Pin(22))) BACKGROUND = 0x491D88 PALETTE_0 = 0xFEC859 PALETTE_1 = 0xFA448C PALETTE_2 = 0x331A38 PALETTE_3 = 0x43B5A0 IIR_FILTER_TIME_S = 5 def reboot(pressed): if pressed: exit_python() buttons.attach(buttons.BTN_HOME, reboot) # define functions to round, floor and ceil with float resolutions def round_res(num, res): return round(num / res) * res def floor_res(num, res): return floor(num / res) * res def ceil_res(num, res): return ceil(num / res) * res def map_vals_fn(in_min, in_max, out_min, out_max): scaleFactor = float(out_max - out_min) / float(in_max - in_min) def map_vals(value): return out_min + (value - in_min) * scaleFactor return map_vals # generic function to draw samples in a given area on the display def draw_samples( samples, x_min=0, x_max=display.width(), y_min=0, y_max=display.height(), padding=0.05, grid=True, n_grid=5, ): keys, values = list(zip(*samples)) min_key = min(keys) max_key = max(keys) min_value = min(values) max_value = max(values) width = x_max - x_min height = y_max - y_min x_map_fn = map_vals_fn( min_key, max_key, x_min + padding * width, x_min + (1 - padding) * width ) y_map_fn = map_vals_fn( max_value, min_value, x_min + padding * height, x_min + (1 - padding) * height, ) xs = map(int, map(x_map_fn, keys)) ys = map(int, map(y_map_fn, values)) nodes = list(zip(xs, ys)) if grid: key_res = 10 ** round(log(max_key - min_key, 10)) / n_grid value_res = 10 ** round(log(max_value - min_value, 10)) / n_grid min_key_grid = round_res(min_key, key_res) min_value_grid = round_res(min_value, value_res) n_key_grids = ceil((max_key - min_key_grid) / key_res + 0.5) n_value_grids = ceil((max_value - min_value_grid) / value_res + 0.5) for x_grid_idx in range(n_key_grids): x = x_map_fn(min_key_grid + x_grid_idx * key_res) display.drawLine(x, y_min, x, y_max, PALETTE_2) for y_grid_idx in range(n_value_grids): y = y_map_fn(min_value_grid + y_grid_idx * value_res) display.drawLine(x_min, y, x_max, y, PALETTE_2) for idx in range(len(nodes) - 1): display.drawLine( nodes[idx][0], nodes[idx][1], nodes[idx + 1][0], nodes[idx + 1][1], PALETTE_3, ) samples = [(ticks_ms(), bme.pressure)] while True: try: display.drawFill(BACKGROUND) current_ticks_ms = ticks_ms() current_pressure = bme.pressure diff_ticks_ms = current_ticks_ms - samples[-1][0] # apply single pole IIR filter # use 1/5 of IIR_FILTER_TIME_S, as 97% of signal level will then be achieve within IIR_FILTER_TIME_S alpha = (diff_ticks_ms) / ((diff_ticks_ms) + IIR_FILTER_TIME_S * 10 ** 3 / 5) fitered_presure = samples[-1][1] + alpha * (current_pressure - samples[-1][1]) samples.append((current_ticks_ms, fitered_presure)) draw_samples(samples, y_max=display.height() * 4 // 5) display.drawText( 22-display.height() // 20, display.height() * 19 // 20 - 22, "{} mbar".format(current_pressure), PALETTE_3, "roboto_regular22", ) display.drawText( display.width() * 2 // 3, display.height() * 19 // 20 - 24, " press any\r\nbutton to exit", PALETTE_1, "roboto_regular12", ) display.flush() # if screen is full, remove oldest sample if len(samples) > (display.width() / 3): samples = samples[1:] sleep(0) except: exit_python()