usb-esp-programmer

Pinout — USB-C ESP Programmer (HC22002)

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Target header (programmer → target):

Signal	Direction	Connect to ESP
GND	—	GND
VCC	out (optional)	3V3 — only if powering the target from the programmer
TX	out	target RX
RX	in	target TX
EN (RST)	out	EN / reset (driven by the auto-reset circuit)
IO0 (BOOT)	out	IO0 / boot strap (driven by the auto-reset circuit)

• Logic level: 3.3 V.
• Cross TX↔RX (programmer TX goes to target RX, and vice-versa).

Pull-up jumpers (JP1 / JP2)

Next to the target header are two small 2-pin jumpers. Each one connects an optional pull-up onto one of the ESP’s two strapping pins:

Jumper	Pull-up on	ESP pin
JP1	EN / RESET	chip-enable
JP2	IO0 / BOOT	boot strap

• Jumper cap fitted = pull-up ON. Cap removed = that line is left to the target.
• Ships with both caps fitted (both pull-ups enabled) — the default that works for most targets.

What they do. EN and IO0 must idle high for an ESP to run and boot normally — the auto-reset circuit only pulses them low for the moment of flashing. A bare ESP module or a minimal custom board with no pull-ups of its own can fail to boot or hang in reset. These jumpers give those two pins a clean high idle level so flashing just works out of the box.

When to remove a cap:

• Your target board already has its own EN/IO0 pull-ups (most dev boards do). Two in parallel is usually harmless, but pull the cap(s) if you see boot or flashing flakiness.
• You need EN or IO0 fully released so the target can drive it.
• Leave them fitted whenever bringing up a bare module — that’s what they’re for.

(JP1/JP2 are marked on the board silkscreen. Exact header pin order/pitch and electrical limits: see the product page.)

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