fix: warn of radio pins that block flashing over USB

GPIO2 on the original ESP32, 46 on the S2/S3 and 8 on the C3/C6 don't stop
a normal boot, but held at the wrong level at reset they keep esptool from
starting the download mode.  The WT32-ETH01 wiring puts TX on GPIO2.

Each warning now says what the pin does and what to do: move it for a pin
that stops the boot, disconnect it to flash for one that only blocks USB.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
cjkas 2026-10-29 22:54:11 +01:00
parent 658f5eabeb
commit 92e69d599f
6 changed files with 87 additions and 40 deletions

View file

@ -1,13 +1,14 @@
// The strapping pins whose level at reset can keep each chip from starting
// the firmware, as src/BootPins.h has them for the log. A radio that drives
// one at power-up stops the board booting until EN is pressed (issue #34).
// Keep the pins, the radio pins checked and the shared RX/TX rule in step
// with that file.
// the firmware, or from being flashed over USB, as src/BootPins.h has them
// for the log. A radio that drives one at reset stops the board booting
// until EN is pressed (issue #34), or esptool from connecting. Keep the
// pins, the radio pins checked and the shared RX/TX rule in step with that
// file.
// The minify step joins this file into index.js; Node loads it on its own for
// the tests (test/js).
class BootPins {
// A warning for each of the radio config's pins that can stop the board
// booting.
// booting or being flashed.
static radioWarnings(chipModel, config) {
const chip = BootPins.CHIPS[chipModel || ''] || {};
const warnings = [];
@ -15,24 +16,28 @@ class BootPins {
const pin = config[field];
if (field === 'RXPin' && pin === config.TXPin) continue;
const effect = chip[pin];
if (effect) warnings.push(`${name} is on GPIO-${pin}, a strapping pin: ${effect}. The radio can hold it there and stop the board booting after a power cut, so move it to another pin.`);
if (effect) warnings.push(`${name} is on GPIO-${pin}, a strapping pin the radio can drive at reset. ${effect}`);
}
return warnings;
}
}
BootPins.DOWNLOAD = 'Held low, it starts the download mode instead of the firmware: move it to another pin.';
BootPins.FLASH_1V8 = 'Held high, it powers the flash at 1.8 V and the board bootloops: move it to another pin.';
BootPins.NO_USB_HIGH = 'Held high, it stops flashing over USB, so disconnect it to flash.';
BootPins.NO_USB_LOW = 'Held low, it stops flashing over USB, so disconnect it to flash.';
// By the chip model the header sends, '' for the original ESP32.
BootPins.CHIPS = {
'': { 0: 'low at reset starts the download mode', 12: 'high at reset powers the flash at 1.8 V' },
s2: { 0: 'low at reset starts the download mode', 45: 'high at reset powers the flash at 1.8 V' },
s3: { 0: 'low at reset starts the download mode', 45: 'high at reset powers the flash at 1.8 V' },
c3: { 9: 'low at reset starts the download mode' },
c5: { 28: 'low at reset starts the download mode' },
c6: { 9: 'low at reset starts the download mode' },
p4: { 35: 'low at reset starts the download mode' },
p4es: { 35: 'low at reset starts the download mode' }
'': { 0: BootPins.DOWNLOAD, 12: BootPins.FLASH_1V8, 2: BootPins.NO_USB_HIGH },
s2: { 0: BootPins.DOWNLOAD, 45: BootPins.FLASH_1V8, 46: BootPins.NO_USB_HIGH },
s3: { 0: BootPins.DOWNLOAD, 45: BootPins.FLASH_1V8, 46: BootPins.NO_USB_HIGH },
c3: { 9: BootPins.DOWNLOAD, 8: BootPins.NO_USB_LOW },
c5: { 28: BootPins.DOWNLOAD },
c6: { 9: BootPins.DOWNLOAD, 8: BootPins.NO_USB_LOW },
p4: { 35: BootPins.DOWNLOAD },
p4es: { 35: BootPins.DOWNLOAD }
};
// The radio pins the CC1101 drives at power-up, before it is set up: GDO0
// puts out a clock, GDO2 CHIP_RDYn, and SO follows CHIP_RDYn while CSN is
// low.
// The radio pins the CC1101 drives: at power-up GDO0 puts out a clock, GDO2
// CHIP_RDYn, and SO follows CHIP_RDYn while CSN is low. Once it is set up,
// GDO2 puts out what it hears.
BootPins.RADIO_PINS = [['TXPin', 'TX'], ['RXPin', 'RX'], ['MISOPin', 'MISO']];
if (typeof module !== 'undefined' && module.exports) module.exports = { BootPins };

View file

@ -6,30 +6,37 @@
#endif
// The strapping pins whose level at reset can keep the chip from starting
// the firmware. The ROM reads them before any code runs, so a radio that
// drives one at power-up stops the board booting until EN is pressed (issue
// #34). The strapping pins that only pick a download mode, quiet the boot
// log or set the SDIO timing aren't listed. The web UI has the same pins in
// data-src/js/pins.js, and checks the same radio pins as
// transceiver_config_t::apply(): keep the three in step.
//
// Returns what the pin does at reset, or nullptr for a pin that can't stop
// the boot.
// the firmware, or from being flashed over USB. The ROM reads them before
// any code runs, so a radio that drives one at reset stops the board booting
// until EN is pressed (issue #34), or esptool from connecting. The strapping
// pins that only quiet the boot log or set the SDIO timing aren't listed.
// The web UI has the same pins in data-src/js/pins.js, and checks the same
// radio pins as transceiver_config_t::apply(): keep the three in step.
constexpr const char *BOOT_PIN_DOWNLOAD = "Held low, it starts the download mode instead of the firmware: move it to another pin.";
constexpr const char *BOOT_PIN_FLASH_1V8 = "Held high, it powers the flash at 1.8 V and the board bootloops: move it to another pin.";
constexpr const char *BOOT_PIN_NO_USB_HIGH = "Held high, it stops flashing over USB, so disconnect it to flash.";
constexpr const char *BOOT_PIN_NO_USB_LOW = "Held low, it stops flashing over USB, so disconnect it to flash.";
// Returns what the pin does at reset and what to do, or nullptr for a pin
// that is safe.
inline const char *bootPinEffect(uint8_t pin) {
#if defined(CONFIG_IDF_TARGET_ESP32S2) || defined(CONFIG_IDF_TARGET_ESP32S3)
if(pin == 0) return "low at reset starts the download mode";
if(pin == 45) return "high at reset powers the flash at 1.8 V";
if(pin == 0) return BOOT_PIN_DOWNLOAD;
if(pin == 45) return BOOT_PIN_FLASH_1V8;
if(pin == 46) return BOOT_PIN_NO_USB_HIGH;
#elif defined(CONFIG_IDF_TARGET_ESP32C3) || defined(CONFIG_IDF_TARGET_ESP32C6)
if(pin == 9) return "low at reset starts the download mode";
if(pin == 9) return BOOT_PIN_DOWNLOAD;
if(pin == 8) return BOOT_PIN_NO_USB_LOW;
#elif defined(CONFIG_IDF_TARGET_ESP32C5)
if(pin == 28) return "low at reset starts the download mode";
if(pin == 28) return BOOT_PIN_DOWNLOAD;
#elif defined(CONFIG_IDF_TARGET_ESP32P4)
if(pin == 35) return "low at reset starts the download mode";
if(pin == 35) return BOOT_PIN_DOWNLOAD;
#else
// The original ESP32. MTDI picks the flash voltage unless the
// VDD_SDIO efuses are burned.
if(pin == 0) return "low at reset starts the download mode";
if(pin == 12) return "high at reset powers the flash at 1.8 V";
if(pin == 0) return BOOT_PIN_DOWNLOAD;
if(pin == 12) return BOOT_PIN_FLASH_1V8;
if(pin == 2) return BOOT_PIN_NO_USB_HIGH;
#endif
return nullptr;
}

View file

@ -577,7 +577,7 @@ void transceiver_config_t::load() {
}
static void warnBootPin(const char *name, uint8_t pin) {
const char *effect = bootPinEffect(pin);
if(effect) ESP_LOGW(TAG, "Radio %s is on GPIO%u, a strapping pin: %s. The radio can hold it there and stop the board booting after a power cut, so move it to another pin.", name, pin, effect);
if(effect) ESP_LOGW(TAG, "Radio %s is on GPIO%u, a strapping pin the radio can drive at reset. %s", name, pin, effect);
}
void transceiver_config_t::apply() {
Preferences pref;
@ -603,9 +603,10 @@ void transceiver_config_t::apply() {
pref.end();
if(!radioInit) return;
ESP_LOGD(TAG, "Applying radio settings - Setting Data Pins RX:%u TX:%u", this->RXPin, this->TXPin);
// The pins the CC1101 drives at power-up, before it is set up: GDO0
// puts out a clock, GDO2 CHIP_RDYn, and SO follows CHIP_RDYn while CSN
// is low. The web UI checks the same (data-src/js/pins.js).
// The pins the CC1101 drives: at power-up GDO0 puts out a clock, GDO2
// CHIP_RDYn, and SO follows CHIP_RDYn while CSN is low. Once it is
// set up, GDO2 puts out what it hears. The web UI checks the same
// (data-src/js/pins.js).
warnBootPin("TX", this->TXPin);
if(this->RXPin != this->TXPin) warnBootPin("RX", this->RXPin);
warnBootPin("MISO", this->MISOPin);

View file

@ -18,6 +18,22 @@ test('RX on GPIO12 warns of the flash voltage on the original ESP32', () => {
assert.match(warnings[0], /1\.8 V/);
});
test('TX on GPIO2 warns of flashing over USB on the original ESP32', () => {
// The WT32-ETH01 wiring in the wiki.
const warnings = BootPins.radioWarnings('', Object.assign({}, esp32Defaults, { TXPin: 2 }));
assert.equal(warnings.length, 1);
assert.match(warnings[0], /^TX is on GPIO-2, .*Held high, it stops flashing over USB, so disconnect it to flash\.$/);
});
test('GPIO8 held low blocks flashing on the C3 and C6', () => {
const config = { SCKPin: 4, CSNPin: 7, MOSIPin: 6, MISOPin: 5, TXPin: 10, RXPin: 8 };
for (const chip of ['c3', 'c6']) {
const warnings = BootPins.radioWarnings(chip, config);
assert.equal(warnings.length, 1);
assert.match(warnings[0], /^RX is on GPIO-8, .*Held low, it stops flashing over USB/);
}
});
test('an unknown chip model warns of nothing', () => {
assert.deepEqual(BootPins.radioWarnings('h2', Object.assign({}, esp32Defaults, { RXPin: 12 })), []);
});

View file

@ -19,10 +19,18 @@ static void test_gpio0_picks_the_boot_mode() {
TEST_ASSERT_NOT_NULL(strstr(effect, "download mode"));
}
static void test_gpio2_blocks_flashing_over_usb() {
// It only counts with GPIO0 low, so the board boots, but esptool can't
// start the download mode while it is high.
const char *effect = bootPinEffect(2);
TEST_ASSERT_NOT_NULL(effect);
TEST_ASSERT_NOT_NULL(strstr(effect, "high"));
TEST_ASSERT_NOT_NULL(strstr(effect, "USB"));
}
static void test_harmless_strapping_pins_are_not_listed() {
// 2 only matters for the download mode, 5 and 15 set the SDIO timing and
// the boot log. 5 is the default CSN.
TEST_ASSERT_NULL(bootPinEffect(2));
// 5 and 15 set the SDIO timing and quiet the boot log. 5 is the default
// CSN.
TEST_ASSERT_NULL(bootPinEffect(5));
TEST_ASSERT_NULL(bootPinEffect(15));
}
@ -34,14 +42,17 @@ static void test_default_radio_pins_are_safe() {
}
static void test_other_chips_boot_pins_are_safe_here() {
TEST_ASSERT_NULL(bootPinEffect(8));
TEST_ASSERT_NULL(bootPinEffect(9));
TEST_ASSERT_NULL(bootPinEffect(45));
TEST_ASSERT_NULL(bootPinEffect(46));
}
int main(int, char **) {
UNITY_BEGIN();
RUN_TEST(test_gpio12_picks_the_flash_voltage);
RUN_TEST(test_gpio0_picks_the_boot_mode);
RUN_TEST(test_gpio2_blocks_flashing_over_usb);
RUN_TEST(test_harmless_strapping_pins_are_not_listed);
RUN_TEST(test_default_radio_pins_are_safe);
RUN_TEST(test_other_chips_boot_pins_are_safe_here);

View file

@ -17,6 +17,12 @@ static void test_gpio0_picks_the_boot_mode() {
TEST_ASSERT_NOT_NULL(bootPinEffect(0));
}
static void test_gpio46_blocks_flashing_over_usb() {
const char *effect = bootPinEffect(46);
TEST_ASSERT_NOT_NULL(effect);
TEST_ASSERT_NOT_NULL(strstr(effect, "USB"));
}
static void test_gpio12_is_safe() {
// 12 is the S3's default SCK.
TEST_ASSERT_NULL(bootPinEffect(12));
@ -32,6 +38,7 @@ int main(int, char **) {
UNITY_BEGIN();
RUN_TEST(test_gpio45_picks_the_flash_voltage);
RUN_TEST(test_gpio0_picks_the_boot_mode);
RUN_TEST(test_gpio46_blocks_flashing_over_usb);
RUN_TEST(test_gpio12_is_safe);
RUN_TEST(test_default_radio_pins_are_safe);
return UNITY_END();