I tried Quad I/O (--flash_mode qio) but the exact same thing happens: The flash process succeeds (even verifies the checksum OK) but rebooting gives "csum err":
[00]
ets Jan 8 2013,rst cause:2, boot mode:(3,7)
load 0x40100000, len 27444, 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
I'm used to embedded/electronics being difficult, but is this normally this hard to achieve? The setup I'm using (per an Instructable) is:
TXD -> RXD on USB/Serial unit
CHPD -> 3.3V
RST: unconnected
VCC -> 3.3V
GND -> GND
GP2: unconnected
GP0 -> GND
RXD -> TXD on USB/Serial unit
Does this look correct? The USB/Serial unit is powered from USB, so it's running at 5V. Is this a problem for comms between usb/serial (PC) and the ESP?