/*************************************************************************** * __________ __ ___. * Open \______ \ ____ ____ | | _\_ |__ _______ ___ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ * \/ \/ \/ \/ \/ * $Id$ * * Copyright (C) 2012 by Amaury Pouly * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * ****************************************************************************/ #include "touchscreen-imx233.h" #include "stdlib.h" /* Description: * the driver basically has 2 modes: * - wait mode: use the hardware touch detect mechanism to wait for an edge * - measurement mode: use pull up/down and adc to measure X/Y * In measurement mode, we start by measuring X then Y then we check if * the hardware still detect a touch. When no touch is detected anymore, we * go back to wait mode. * For each axis, we handle stabilization by repeatedly measuring the position * until it is stable. We consider a set of measures stable when * no measure is further away from the average than DEBOUNCE_THRESHOLD and * we have at least SAMPLES_THRESHOLD measures. This avoids using magic * timing constants specific to the touchscreen stabilization time and * it is much more robust. * * Inspired by linux touchscreen driver for the stmp37xx. */ enum touch_state_t { TOUCH_STATE_WAIT, /* wait for touch */ TOUCH_STATE_MEASURE_X, /* measure x */ TOUCH_STATE_MEASURE_Y, /* measure y */ TOUCH_STATE_VERIFY, /* verify touch */ }; #define DEBOUNCE_THRESHOLD 100 #define SAMPLES_THRESHOLD 4 static enum touch_state_t touch_state; static int touch_chan = -1; static int touch_delay = -1; static int touch_x, touch_y, nr_samples; /* once a touch is confirmed, the parameters are copied to these value for * instant readout by button code. */ static bool old_touch_detect = false; static int old_touch_x, old_touch_y; static void kick_measure(bool pull_x, bool pull_y, bool detect, int lradc_phys) { /* setup measurement: x- pull down and x+ pull up */ imx233_lradc_setup_touch(pull_x, pull_y, pull_x, pull_y, detect); imx233_lradc_enable_touch_detect_irq(false); imx233_lradc_enable_channel_irq(touch_chan, true); /* measure channel, no accumulation */ imx233_lradc_setup_channel(touch_chan, false, false, 0, lradc_phys); /* use a delay */ imx233_lradc_setup_delay(touch_delay, 1 << touch_chan, 0, 0, 8); imx233_lradc_kick_delay(touch_delay); } static void enter_state(enum touch_state_t state) { touch_state = state; switch(state) { case TOUCH_STATE_WAIT: imx233_lradc_setup_touch(false, false, false, false, true); imx233_lradc_enable_channel_irq(touch_chan, false); imx233_lradc_enable_touch_detect_irq(true); break; case TOUCH_STATE_MEASURE_X: kick_measure(true, false, false, LRADC_SRC_YPLUS); break; case TOUCH_STATE_MEASURE_Y: kick_measure(false, true, false, LRADC_SRC_XPLUS); break; case TOUCH_STATE_VERIFY: kick_measure(false, false, true, LRADC_SRC_YPLUS); break; } } static void process(void) { int val; switch(touch_state) { case TOUCH_STATE_WAIT: /* a touch has happened, check if it's still valid */ if(imx233_lradc_read_touch_detect()) enter_state(TOUCH_STATE_MEASURE_X); else { old_touch_detect = false; /* clear detect interrupt */ imx233_lradc_clear_touch_detect_irq(); } break; case TOUCH_STATE_MEASURE_X: /* read value */ val = imx233_lradc_read_channel(touch_chan); /* if value is too far from average, restart */ if(nr_samples > 0 && abs(val - touch_x) > DEBOUNCE_THRESHOLD) nr_samples = 0; touch_x = (touch_x * nr_samples + val) / (nr_samples + 1); nr_samples++; /* if we have enough samples, measure Y */ if(nr_samples > SAMPLES_THRESHOLD) enter_state(TOUCH_STATE_MEASURE_Y); else imx233_lradc_kick_delay(touch_delay); break; case TOUCH_STATE_MEASURE_Y: /* read value */ val = imx233_lradc_read_channel(touch_chan); /* if value is too far from average, restart */ if(nr_samples > 0 && abs(val - touch_y) > DEBOUNCE_THRESHOLD) nr_samples = 0; touch_y = (touch_y * nr_samples + val) / (nr_samples + 1); nr_samples++; /* if we have enough samples, verify touch */ if(nr_samples > SAMPLES_THRESHOLD) enter_state(TOUCH_STATE_VERIFY); else imx233_lradc_kick_delay(touch_delay); break; case TOUCH_STATE_VERIFY: if(imx233_lradc_read_touch_detect()) { old_touch_detect = true; old_touch_x = touch_x; old_touch_y = touch_y; enter_state(TOUCH_STATE_MEASURE_X); } else { old_touch_detect = false; enter_state(TOUCH_STATE_WAIT); } break; } } void INT_TOUCH_DETECT(void) { process(); } static void touch_channel_irq(int chan) { (void) chan; process(); } void imx233_touchscreen_init(void) { touch_chan = imx233_lradc_acquire_channel(TIMEOUT_NOBLOCK); touch_delay = imx233_lradc_acquire_delay(TIMEOUT_NOBLOCK); if(touch_chan < 0 || touch_delay < 0) panicf("Cannot acquire channel and delays for touchscreen measurement"); imx233_touchscreen_enable(false); } void imx233_touchscreen_enable(bool enable) { enter_state(TOUCH_STATE_WAIT); imx233_lradc_set_channel_irq_callback(touch_chan, &touch_channel_irq); imx233_icoll_enable_interrupt(INT_SRC_LRADC_CHx(touch_chan), enable); imx233_icoll_enable_interrupt(INT_SRC_TOUCH_DETECT, enable); } bool imx233_touchscreen_get_touch(int *raw_x, int *raw_y) { if(raw_x) *raw_x = old_touch_x; if(raw_y) *raw_y = old_touch_y; return old_touch_detect; }