ESP32-S3 GPIO3 does not select external JTAG when low

[straubm]

Hi team,

this is my first post here.

I want to use ESP32-S3 with an external JTAG (ESPPROG). So I strapped GPIO3 to GND as documented.
Nevertheless, the external JTAG does not work. The connections are correct, and my ESPPROG worked ok with ESP32.

Any ideas appreciated.

[UnknownBot]

Hello there!

Please make sure your EFUSE values are set properly:
EFUSE_DIS_USB_JTAG = 0
EFUSE_DIS_PAD_JTAG = 0
EFUSE_STRAP_JTAG_SEL=1

Setting these "should" make sure that you can set the GPIO3 Strapping pin.
You could also permanently set it to External JTAG using:
EFUSE_DIS_USB_JTAG = 1
EFUSE_DIS_PAD_JTAG =0
EFUSE_STRAP_JTAG_SEL = Doesn't matter

[straubm]

Hi there,

thx. I am experienced in programming but new to ESP32 (came from STM32), so please bear with me

I did find DIS_USB_JTAG and DIS_PAD_JTAG, but not STRAP_JTAG_SEL.

This is my efuse summary:

```
C:\Users\offic>espefuse.py -p COM4 summary
Connecting....
Detecting chip type... ESP32-S3
espefuse.py v3.3-dev

=== Run "summary" command ===
EFUSE_NAME (Block) Description = [Meaningful Value] [Readable/Writeable] (Hex Value)
----------------------------------------------------------------------------------------
Config fuses:
DIS_ICACHE (BLOCK0) Disables ICache = False R/W (0b0)
DIS_DCACHE (BLOCK0) Disables DCache = False R/W (0b0)
DIS_DOWNLOAD_ICACHE (BLOCK0) Disables Icache when SoC is in Download mode = False R/W (0b0)
DIS_DOWNLOAD_DCACHE (BLOCK0) Disables Dcache when SoC is in Download mode = False R/W (0b0)
DIS_FORCE_DOWNLOAD (BLOCK0) Disables forcing chip into Download mode = False R/W (0b0)
DIS_CAN (BLOCK0) Disables the TWAI Controller hardware = False R/W (0b0)
DIS_APP_CPU (BLOCK0) Disables APP CPU = False R/W (0b0)
FLASH_TPUW (BLOCK0) Configures flash startup delay after SoC power-up, = 0 R/W (0x0)
unit is (ms/2). When the value is 15, delay is 7.
5 ms
DIS_LEGACY_SPI_BOOT (BLOCK0) Disables Legacy SPI boot mode = False R/W (0b0)
UART_PRINT_CHANNEL (BLOCK0) Selects the default UART for printing boot msg = UART0 R/W (0b0)
FLASH_ECC_MODE (BLOCK0) Configures the ECC mode for SPI flash
= 16-byte to 18-byte mode R/W (0b0)
DIS_USB_DOWNLOAD_MODE (BLOCK0) Disables USB OTG download feature in UART download = False R/W (0b0)
boot mode
UART_PRINT_CONTROL (BLOCK0) Sets the default UART boot message output mode = Enabled R/W (0b00)
FLASH_TYPE (BLOCK0) Selects SPI flash type = 4 data lines R/W (0b0)
FLASH_PAGE_SIZE (BLOCK0) Sets the size of flash page = 0 R/W (0b00)
FLASH_ECC_EN (BLOCK0) Enables ECC in Flash boot mode = False R/W (0b0)
FORCE_SEND_RESUME (BLOCK0) Forces ROM code to send an SPI flash resume comman = False R/W (0b0)
d during SPI boot
BLOCK_USR_DATA (BLOCK3) User data
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W

Efuse fuses:
WR_DIS (BLOCK0) Disables programming of individual eFuses = 0 R/W (0x00000000)
RD_DIS (BLOCK0) Disables software reading from BLOCK4-10 = 0 R/W (0b0000000)

Identity fuses:
SECURE_VERSION (BLOCK0) Secure version (used by ESP-IDF anti-rollback feat = 0 R/W (0x0000)
ure)
MAC (BLOCK1) Factory MAC Address
= 7c:df:a1:e3:69:c0 (OK) R/W
WAFER_VERSION (BLOCK1) WAFER version = 1 R/W (0b001)
PKG_VERSION (BLOCK1) ??? Package version = ESP32-S3 R/W (0x0)
BLOCK1_VERSION (BLOCK1) ??? BLOCK1 efuse version = 1 R/W (0b001)
OPTIONAL_UNIQUE_ID (BLOCK2) ??? Optional unique 128-bit ID
= ba 3b 50 b7 a0 ee e5 17 51 aa c5 30 21 32 6b 72 R/W
BLOCK2_VERSION (BLOCK2) ??? Version of BLOCK2 = 2 R/W (0b010)
CUSTOM_MAC (BLOCK3) Custom MAC Address
= 00:00:00:00:00:00 (OK) R/W

Security fuses:
SOFT_DIS_JTAG (BLOCK0) Software disables JTAG by programming odd number o = 0 R/W (0b000)
f 1 bit(s). JTAG can be re-enabled via HMAC periph
eral
HARD_DIS_JTAG (BLOCK0) Hardware disables JTAG permanently = False R/W (0b0)
DIS_DOWNLOAD_MANUAL_ENCRYPT (BLOCK0) Disables flash encryption when in download boot mo = False R/W (0b0)
des
SPI_BOOT_CRYPT_CNT (BLOCK0) Enables encryption and decryption, when an SPI boo = Disable R/W (0b000)
t mode is set. Enabled when 1 or 3 bits are set,di
sabled otherwise
SECURE_BOOT_KEY_REVOKE0 (BLOCK0) Revokes use of secure boot key digest 0 = False R/W (0b0)
SECURE_BOOT_KEY_REVOKE1 (BLOCK0) Revokes use of secure boot key digest 1 = False R/W (0b0)
SECURE_BOOT_KEY_REVOKE2 (BLOCK0) Revokes use of secure boot key digest 2 = False R/W (0b0)
KEY_PURPOSE_0 (BLOCK0) KEY0 purpose = USER R/W (0x0)
KEY_PURPOSE_1 (BLOCK0) KEY1 purpose = USER R/W (0x0)
KEY_PURPOSE_2 (BLOCK0) KEY2 purpose = USER R/W (0x0)
KEY_PURPOSE_3 (BLOCK0) KEY3 purpose = USER R/W (0x0)
KEY_PURPOSE_4 (BLOCK0) KEY4 purpose = USER R/W (0x0)
KEY_PURPOSE_5 (BLOCK0) KEY5 purpose = USER R/W (0x0)
SECURE_BOOT_EN (BLOCK0) Enables secure boot = False R/W (0b0)
SECURE_BOOT_AGGRESSIVE_REVOKE (BLOCK0) Enables aggressive secure boot key revocation mode = False R/W (0b0)
STRAP_JTAG_SEL (BLOCK0) Enable selection between usb_to_jtagor pad_to_jtag = False R/W (0b0)
through GPIO3
DIS_DOWNLOAD_MODE (BLOCK0) Disables all Download boot modes = False R/W (0b0)
ENABLE_SECURITY_DOWNLOAD (BLOCK0) Enables secure UART download mode (read/write flas = False R/W (0b0)
h only)
BLOCK_KEY0 (BLOCK4)
Purpose: USER
Encryption key0 or user data
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W
BLOCK_KEY1 (BLOCK5)
Purpose: USER
Encryption key1 or user data
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W
BLOCK_KEY2 (BLOCK6)
Purpose: USER
Encryption key2 or user data
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W
BLOCK_KEY3 (BLOCK7)
Purpose: USER
Encryption key3 or user data
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W
BLOCK_KEY4 (BLOCK8)
Purpose: USER
Encryption key4 or user data
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W
BLOCK_KEY5 (BLOCK9)
Purpose: USER
Encryption key5 or user data
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W
BLOCK_SYS_DATA2 (BLOCK10) System data (part 2)
= 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 R/W

Spi_Pad_Config fuses:
SPI_PAD_CONFIG_CLK (BLOCK1) SPI CLK pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_Q (BLOCK1) SPI Q (D1) pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_D (BLOCK1) SPI D (D0) pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_CS (BLOCK1) SPI CS pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_HD (BLOCK1) SPI HD (D3) pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_WP (BLOCK1) SPI WP (D2) pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_DQS (BLOCK1) SPI DQS pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_D4 (BLOCK1) SPI D4 pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_D5 (BLOCK1) SPI D5 pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_D6 (BLOCK1) SPI D6 pad = 0 R/W (0b000000)
SPI_PAD_CONFIG_D7 (BLOCK1) SPI D7 pad = 0 R/W (0b000000)

Usb Config fuses:
DIS_USB (BLOCK0) Disables the USB OTG hardware = False R/W (0b0)
USB_EXCHG_PINS (BLOCK0) Exchanges USB D+ and D- pins = False R/W (0b0)
EXT_PHY_ENABLE (BLOCK0) Enables external USB PHY = False R/W (0b0)
BTLC_GPIO_ENABLE (BLOCK0) Enables BTLC GPIO = 0 R/W (0b00)
DIS_USB_JTAG (BLOCK0) Disable usb_serial_jtag-to-jtag function = False R/W (0b0)
DIS_USB_SERIAL_JTAG (BLOCK0) Disable usb_serial_jtag module = False R/W (0b0)
USB_PHY_SEL (BLOCK0) Select internal/external PHY for USB OTGand usb_se = False R/W (0b0)
rial_jtag

Vdd_Spi Config fuses:
VDD_SPI_XPD (BLOCK0) The VDD_SPI regulator is powered on = True R/W (0b1)
VDD_SPI_TIEH (BLOCK0) The VDD_SPI power supply voltage at reset
= Connect to VDD_RTC_IO R/W (0b1)
VDD_SPI_FORCE (BLOCK0) Force using VDD_SPI_XPD and VDD_SPI_TIEH to config = True R/W (0b1)
ure VDD_SPI LDO
PIN_POWER_SELECTION (BLOCK0) Sets default power supply for GPIO33..37 = VDD_SPI R/W (0b1)

Wdt Config fuses:
WDT_DELAY_SEL (BLOCK0) Selects RTC WDT timeout threshold at startup = 0 R/W (0b00)

Flash voltage (VDD_SPI) set to 3.3V by efuse.
```

[straubm]

Hi,

I burnt the efuse regardless, now it shows up in the summary and everything works as expected.

Thanks!