
For comparison, I have been using an ESP-01 module I bought from an Aliexpress vendor. I am using a Saleae logic analyzer because my USB-to-UART module is not capable of the 75000 baud that the bootloader talks.
I am using the flash tool and binaries from version 0.9.2 included with espressif_iot_esp8266_development_kit_20140929.
First of all, the flash tool loaded the 4 bin files successfully at the addresses required for the configuration without cloud upgrade:

I took these flash addresses from the document "7-Espressif IOT Flash 读写说明_v0.2.pdf", page 7. I believe that the flash load was successful because there were no error messages, and the tool displayed my chip's MAC address correctly.
Now, the problem is that when I put GPIO0 back to HIGH (with MTDO still LOW and GPIO2 still HIGH), and I try to boot the AT firmware, the AT "ready" message does not start up. Here is what is displayed from my module at 75000 baud:
Code: Select all
ets Jan 8 2013 rst cause:1 boot mode:(3 6)
load 0x40100000 len 612 room 16
tail 4
chksum 0xef
load 0x00000000 len 0 room 4
tail 0
chksum 0xef
ho 12 tail 0 room 4
load 0x00000000 len 0 room 12
tail 0
chksum 0xef
csum 0xef
csum err
ets_main.c
And nothing happens after that.
Here is what is displayed with my Aliexpress module:
Code: Select all
ets Jan 8 2013 rst cause:1 boot mode:(3 7)
load 0x40100000 len 24236 room 16
tail 12
chksum 0xb7
ho 0 tail 12 room 4
load 0x3ffe8000 len 3008 room 12
tail 4
chksum 0x2c
load 0x3ffe8bc0 len 4816 room 4
tail 12
chksum 0x46
csum 0x46
(After that the AT firmware starts talking at 115200 baud.)
The flash tool appears to have loaded the firmware correctly. My questions are:
- Why does it not boot into the AT firmware as it is supposed to?
- Why is "boot mode" listed as (3, 6) instead of (3 7) as with my functional Aliexpress module?
- I have MTDO=0, GPIO0=1 and GPIO2=1 when I try to boot from flash. Is there something additional I need to do?
- Why are the lengths and checksums apparently wrong?
- Is there something additional I have to do to make the ESP8266 chip boot from the AT firmware I have loaded?