Content from tidal import * from buttons import Buttons from app import TextApp import machine from machine import ADC import time import lodepng from scheduler import get_scheduler import vga2_8x8 as font PATH = "/apps/tidal_oscilloscope/" GREY = color565(0x20, 0x20, 0x20) SAMPLES = 128 # width of scope area = number of samples SCOPE_HEIGHT = 128 SCALES = [[ADC.ATTN_0DB, 100], [ADC.ATTN_6DB, 200], [ADC.ATTN_11DB, 400]] TIMEBASES = [[31, 1], [62, 2], [156, 5], [312, 10], [625, 20], [1562, 50], [3125, 100], [6250, 200], [0, 1000], [0, 2000], [0, 5000], [0, 10000], [0, 20000], [0, 60000]] ACQUIRE_MODE_ASYNC_THRESH = 101 PX_PER_VDIV = 16 PX_PER_HDIV = 32 TRIGGER_WIDTH = 1 MAX_TRIGGER_CYCLES = 256 with open(PATH + "version") as f: VERSION = f.read() class Oscilloscope(TextApp): BG = BLACK FG = WHITE def on_start(self): self.set_rotation(270) super().on_start() def on_activate(self): super().on_activate() (w, h, buf) = lodepng.decode565(PATH + "badgilent.png") display.blit_buffer(buf, 0, 0, w, h) display.text(font, "V{}".format(VERSION), 112, 120, BLUE, WHITE) time.sleep(2.5) display.fill(BLACK) display.fill_rect(SAMPLES, 0, 240-SAMPLES, SCOPE_HEIGHT+1, GREY) # The badge doesn't sleep when connected to USB. # Roll mode is broken when not connected to USB, unless sleeping is disabled - why? get_scheduler().set_sleep_enabled(False) self.should_quit = False self.scale = 0 self.timebase = 4 self.trig = False self.trig_voltage = 0.4 self.buffer0 = bytearray(SAMPLES) self.roll_mode = False self.roll_display_cnt = 0 self.adc_init() self.source = self.get_adc self.draw_info() self.buttons.set_rotation(0) # Something seems to be broken with the buttons when the screen is rotated 90/270 degrees... # self.buttons.on_press(BUTTON_A, lambda: self.buttona()) self.buttons.on_press(JOY_LEFT, lambda: self.btn_ud(-1)) self.buttons.on_press(JOY_RIGHT, lambda: self.btn_ud(1)) self.buttons.on_press(JOY_UP, lambda: self.timebase_set(-1)) self.buttons.on_press(JOY_DOWN, lambda: self.timebase_set(1)) self.start_new_acquisition() def start_new_acquisition(self): if not self.roll_mode and not self.should_quit: self.acq_timer = self.after(0, self.acquisition_start) def on_deactivate(self): self.should_quit = True self.acq_timer.cancel() def clear_buffer(self): self.buffer0 = bytearray(SAMPLES) def px_to_volts(self, val): return val / PX_PER_VDIV * (SCALES[self.scale][1] / 1000) def btn_ud(self, dx): if BUTTON_A.value() == 1: self.scale_set(dx) else: # A held self.trigger_set(dx) def scale_set(self, ds): if 0 <= (self.scale + ds) < len(SCALES): self.scale += ds self.adc_init() if self.roll_mode: self.clear_buffer() self.draw_info() def timebase_set(self, dt): if 0 <= (self.timebase + dt) < len(TIMEBASES): self.timebase += dt self.adc_init() if TIMEBASES[self.timebase][0] == 0: self.roll_mode_init(True, TIMEBASES[self.timebase][1]) else: self.roll_mode_init(False) self.draw_info() def trigger_set(self, dt): self.trig_voltage += dt * 0.5 * SCALES[self.scale][1] / 1000 self.draw_info() def adc_init(self): self.adc0 = ADC(G0, atten=SCALES[self.scale][0]) self.vscaling = int((SCALES[self.scale][1] * 1000) / PX_PER_VDIV) def roll_mode_init(self, roll, ms_per_div=0): if roll: self.roll_mode = True self.acq_timer.cancel() self.clear_buffer() self.acq_timer = self.periodic(ms_per_div/PX_PER_HDIV, self.acquire_rollmode) self.trig = False else: if not self.roll_mode: return self.roll_mode = False self.acq_timer.cancel() self.start_new_acquisition() # Acquisition def get_adc(self): return self.adc0.read_uv() // self.vscaling def acquire_buffer(self, buffer, n, timebase_setting): ts_microseconds = TIMEBASES[timebase_setting][0] # 1 ms/div requires supa hax if timebase_setting == 0: x = 0 for i in range(n): buffer[i] = self.source() x = i * 0.33 # nop() return for i in range(n): t0 = time.ticks_us() buffer[i] = self.source() # Improve timebase accuracy by factoring in the acquisition time # 50 Hz noise on 20ms/div setting should line up with the grid lines t_adc = time.ticks_diff(time.ticks_us(), t0) time.sleep_us(ts_microseconds - t_adc) def acquire_rollmode(self): for i in range(SAMPLES-1): self.buffer0[i] = self.buffer0[i+1] self.buffer0[SAMPLES-1] = self.source() self.roll_display_cnt -= 1 if self.roll_display_cnt < 0: self.after(0, self.draw_samples) # For faster rolling timebases, don't draw every new sample if TIMEBASES[self.timebase][1] == 2000: self.roll_display_cnt = 1 elif TIMEBASES[self.timebase][1] == 1000: self.roll_display_cnt = 3 else: self.roll_display_cnt = 0 def acquire_async(self): if self.roll_mode: self.acq_timer.cancel() return self.buffer0[self.bufidx] = self.adc0.read_uv() // self.vscaling self.bufidx += 1 if self.bufidx == SAMPLES: self.acq_timer.cancel() self.after(0, self.draw_samples) def acquisition_start(self): # Try to trigger, give up after MAX_TRIGGER_CYCLES trig_attempts = 0 trig_state = 0 triggered = 0 trigbuf = bytearray(TRIGGER_WIDTH) trig_level = int(self.trig_voltage * 1000000) // self.vscaling while trig_attempts < MAX_TRIGGER_CYCLES: self.acquire_buffer(trigbuf, TRIGGER_WIDTH, 0) if trig_state == 0: triggered = 1 for val in trigbuf: triggered = triggered & (val < trig_level) if triggered: trig_state = 1 elif trig_state == 1: triggered = 1 for val in trigbuf: triggered = triggered & (val >= trig_level) self.trig = triggered if triggered: break trig_attempts += 1 # If the timebase is too long, get the samples in a timer callback so the UI stays responsive to button presses if TIMEBASES[self.timebase][1] >= ACQUIRE_MODE_ASYNC_THRESH: self.bufidx = 0 self.acq_timer = self.periodic(TIMEBASES[self.timebase][0] / 1000, self.acquire_async) else: self.acquire_buffer(self.buffer0, SAMPLES, self.timebase) self.after(0, self.draw_samples) # Drawing def draw_info(self): display.text(font, "{: 4} mV/div".format(SCALES[self.scale][1]), 148, 16, WHITE, GREY) if TIMEBASES[self.timebase][1] < 1000: display.text(font, "{: 4} ms/div".format(TIMEBASES[self.timebase][1]), 148, 28, WHITE, GREY) else: display.text(font, "{: 4.0f} s/div ".format(TIMEBASES[self.timebase][1] / 1000), 148, 28, RED, GREY) if self.roll_mode: trig_msg = " " else: trig_msg = "Trig: {:.2f} V".format(self.trig_voltage) display.text(font, trig_msg, 140, 40, WHITE, GREY) display.text(font, "Src: Pin G0", 148, 52, YELLOW, GREY) def draw_samples(self): if self.should_quit: return # To reduce flicker, clear and redraw one horizontal division at a time trig_level = int(self.trig_voltage * 1000000) // self.vscaling HDIVS = 4 for div in range(HDIVS): x0 = div * PX_PER_HDIV display.fill_rect(x0, 0, PX_PER_HDIV, SCOPE_HEIGHT, BLACK) # Vertical gridlines display.line(x0+PX_PER_HDIV-1, 0, x0+PX_PER_HDIV-1, SCOPE_HEIGHT, GREY) # Horizontal gridlines for j in range(8): display.line(x0, SCOPE_HEIGHT-j*PX_PER_VDIV, x0+PX_PER_HDIV, SCOPE_HEIGHT-j*PX_PER_VDIV, GREY) # Trigger level if not self.roll_mode: display.line(x0, SCOPE_HEIGHT-1-trig_level, x0+PX_PER_HDIV-1, SCOPE_HEIGHT-1-trig_level, GREEN) # Trace pidx = 0 if x0 > 0: pidx = x0 - 1 prev_y = SCOPE_HEIGHT-1 - self.buffer0[pidx] prev_x = x0 for x1 in range(PX_PER_HDIV): x = x0 + x1 y = SCOPE_HEIGHT-1 - self.buffer0[x] display.line(prev_x, prev_y, x, y, YELLOW) prev_x = x prev_y = y # Sidebar display.text(font, "Trig'd" if self.trig else " ", 132, 4, GREEN, GREY) # Measurements val_max = max(self.buffer0) val_min = min(self.buffer0) val_avg = sum(self.buffer0) / len(self.buffer0) display.text(font, "Min: {:.2f} V".format(self.px_to_volts(val_min)), 140, 76, YELLOW, GREY) display.text(font, "Max: {:.2f} V".format(self.px_to_volts(val_max)), 140, 88, YELLOW, GREY) display.text(font, "Avg: {:.2f} V".format(self.px_to_volts(val_avg)), 140, 100, YELLOW, GREY) self.start_new_acquisition() main = Oscilloscope