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earlephilhowerearlephilhower
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Allow double-reset to jump to USB bootloader (#893)
Call `rp2040.enableDoubleResetBootloader()` anywhere in the code to enable the check. W/o that call, the checker will be linked in. See #892 CORE1 doesn't start until well after the C runtime initialization, so the flag won't be overwritten. Also increase timeout to 350ms because OTA bootup can be slow.
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‎cores/rp2040/RP2040Support.cpp

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/*
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RP2040 utility class
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Copyright (c) 2021 Earle F. Philhower, III <[email protected]>
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <Arduino.h>
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#include <hardware/structs/psm.h>
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extern "C" void boot_double_tap_check();
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// The following check will never actually execute, but it will cause the boot reset
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// checker to be linked in as part of the constructors.
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void RP2040::enableDoubleResetBootloader() {
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if (psm_hw->done == 0) {
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boot_double_tap_check();
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}
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}

‎cores/rp2040/RP2040Support.h

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@@ -314,6 +314,8 @@ class RP2040 {
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reboot();
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}
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static void enableDoubleResetBootloader();
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void wdt_begin(uint32_t delay_ms) {
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watchdog_enable(delay_ms, 1);
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}

‎cores/rp2040/sdkoverride/pico_bootsel_via_double_reset.c

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/*
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Copyright (c) 2021 Raspberry Pi (Trading) Ltd.
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Hacked by EFP3 to allow disabling unless requested
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SPDX-License-Identifier: BSD-3-Clause
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*/
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#include "pico.h"
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#include "pico/time.h"
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#include "pico/bootrom.h"
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#include "pico/binary_info.h"
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// PICO_CONFIG: PICO_BOOTSEL_VIA_DOUBLE_RESET_TIMEOUT_MS, Window of opportunity for a second press of a reset button to enter BOOTSEL mode (milliseconds), type=int, default=200, group=pico_bootsel_via_double_reset
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#ifndef PICO_BOOTSEL_VIA_DOUBLE_RESET_TIMEOUT_MS
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#define PICO_BOOTSEL_VIA_DOUBLE_RESET_TIMEOUT_MS 350
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#endif
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// PICO_CONFIG: PICO_BOOTSEL_VIA_DOUBLE_RESET_ACTIVITY_LED, Optionally define a pin to use as bootloader activity LED when BOOTSEL mode is entered via reset double tap, type=int, min=0, max=29, group=pico_bootsel_via_double_reset
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// PICO_CONFIG: PICO_BOOTSEL_VIA_DOUBLE_RESET_INTERFACE_DISABLE_MASK, Optionally disable either the mass storage interface (bit 0) or the PICOBOOT interface (bit 1) when entering BOOTSEL mode via double reset, type=int, min=0, max=3, default=0, group=pico_bootsel_via_double_reset
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#ifndef PICO_BOOTSEL_VIA_DOUBLE_RESET_INTERFACE_DISABLE_MASK
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#define PICO_BOOTSEL_VIA_DOUBLE_RESET_INTERFACE_DISABLE_MASK 0u
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#endif
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/** \defgroup pico_bootsel_via_double_reset pico_bootsel_via_double_reset
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When the 'pico_bootsel_via_double_reset' library is linked, a function is
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injected before main() which will detect when the system has been reset
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twice in quick succession, and enter the USB ROM bootloader (BOOTSEL mode)
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when this happens. This allows a double tap of a reset button on a
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development board to be used to enter the ROM bootloader, provided this
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library is always linked.
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*/
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#if !PICO_NO_BI_BOOTSEL_VIA_DOUBLE_RESET
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bi_decl(bi_program_feature("double reset -> BOOTSEL"));
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#endif
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// Doesn't make any sense for a RAM only binary
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#if !PICO_NO_FLASH
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static const uint32_t magic_token[] = {
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0xf01681de, 0xbd729b29, 0xd359be7a,
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};
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// Place our marker on the 2nd core's stack...which will not have been touched when this code is executing
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static uint32_t *magic_location = (uint32_t*)0x20040000;
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//static uint32_t __uninitialized_ram(magic_location)[count_of(magic_token)];
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/* Check for double reset and enter BOOTSEL mode if detected
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This function is registered to run automatically before main(). The
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algorithm is:
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1. Check for magic token in memory; enter BOOTSEL mode if found.
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2. Initialise that memory with that magic token.
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3. Do nothing for a short while (few hundred ms).
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4. Clear the magic token.
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5. Continue with normal boot.
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Resetting the device twice quickly will interrupt step 3, leaving the token
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in place so that the second boot will go to the bootloader.
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*/
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/*static*/ void __attribute__((constructor)) boot_double_tap_check(void) {
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for (uint i = 0; i < count_of(magic_token); i++) {
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if (magic_location[i] != magic_token[i]) {
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// Arm, wait, then disarm and continue booting
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for (i = 0; i < count_of(magic_token); i++) {
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magic_location[i] = magic_token[i];
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}
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busy_wait_us(PICO_BOOTSEL_VIA_DOUBLE_RESET_TIMEOUT_MS * 1000);
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magic_location[0] = 0;
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return;
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}
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}
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// Detected a double reset, so enter USB bootloader
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magic_location[0] = 0;
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#ifdef PICO_BOOTSEL_VIA_DOUBLE_RESET_ACTIVITY_LED
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const uint32_t led_mask = 1u << PICO_BOOTSEL_VIA_DOUBLE_RESET_ACTIVITY_LED;
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#else
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const uint32_t led_mask = 0u;
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#endif
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reset_usb_boot(
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led_mask,
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PICO_BOOTSEL_VIA_DOUBLE_RESET_INTERFACE_DISABLE_MASK
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);
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}
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#endif

‎docs/rp2040.rst

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Returns the total heap that was available to this program at compile time (i.e.
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the Pico RAM size minus things like the ``.data`` and ``.bss`` sections and other
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overhead).
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Bootloader
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----------
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void rp2040.enableDoubleResetBootloader()
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Add a call anywhere in the sketch to ``rp2040.enableDoubleResetBootloader()`` and
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the core will check for a double-tap on reset, and if found will start the USB
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bootloader.

‎keywords.txt

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setFIFOSize KEYWORD2
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setPollingMode KEYWORD2
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enableDoubleResetBootloader KEYWORD2
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OUTPUT_2MA LITERAL1
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OUTPUT_4MA LITERAL1
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OUTPUT_8MA LITERAL1

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