Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)

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By electricdjinn
#96330 Hi!
I am having trouble with a new board that has an ESP-12S module on it (ESP-8266 based). I'm having trouble finding any references to boot mode (3,0), and it is not a great search term.

I removed all the extra connections so all I have are:
RX/TX (confirmed correct RX to TX by seeing the boot message (included at the end of this post):
RTS: goes to ENA pin
CTS: goes to GPIO0
GPIO2 pulled HIGH
GPIO15 grounded
All other pins unconnected; I raised the module up on a couple of layers of Kapton and only bridged those pins to the board or directly to wires from my USB to TTL serial adapter.

When I try to program, all I get is eternal intermittent flashing of the blue LED on the module.

Any ideas? I'm stumped as to where to go next.


Boot message:
ets Jan 8 2013,rst cause:2, boot mode:(3,0)

load 0x40100000, len 1856, room 16
tail 0
chksum 0x63
load 0x3ffe8000, len 776, room 8
tail 0
chksum 0x02
load 0x3ffe8310, len 552, room 8
tail 0
chksum 0x79
csum 0x79

2nd boot version : 1.5
SPI Speed : 40MHz
SPI Mode : DIO
SPI Flash Size & Map: 32Mbit(512KB+512KB)
jump to run user1 @ 1000

rf cal sector: 1017
rf[112] : 00
rf[113] : 00
rf[114] : 01

SDK ver: compiled @ Jul 1 2016 20:04:35
phy ver: 972, pp ver: 10.1
User avatar
By rooppoorali
#96413 The ESP-12S module appears to be in boot mode (3,0). In this boot mode, the module will attempt to boot from the user1.bin firmware image stored in the flash memory.

If you are unable to program the module and the blue LED is flashing intermittently, it may indicate that the module is not properly entering programming mode. This could be caused by a number of factors, including incorrect wiring, a damaged module or USB-to-TTL adapter, or incorrect firmware settings.Make sure that the TX and RX pins are connected correctly and that the RTS pin is connected to the EN pin and the CTS pin is connected to the GPIO0 pin.Check that your USB-to-TTL adapter is supplying the correct voltage to the module (3.3V) and that the GND connections are properly connected.