Using UART

[pfeerick]

It wouldn't have been as funny if I (or someone else) had burnt the CPU. PBP is definitely not a device for the faint hearted.

No, not at all... but like with all modern electronics, reading the datasheets, asking on the forums is obligatory, not optional. Else the magic smoke genie will be released. My poor cubietruck SBC suffered that fate after a couple of years of reliable service... then some fool went and shoved 12v where it ain't supposed to go... that didn't end well  

Voltage wise the PBP is no different to a vast majority of SBCs... having 3.3v logical level IOs, with some are even lower at 1.8v, just to be awkward :O (ok, not quite, but it does make things a tad more difficult).

[VoxUnius]

It wouldn't have been as funny if I (or someone else) had burnt the CPU. PBP is definitely not a device for the faint hearted.

No, not at all... but like with all modern electronics, reading the datasheets, asking on the forums is obligatory, not optional. Else the magic smoke genie will be released. My poor cubietruck SBC suffered that fate after a couple of years of reliable service... then some fool went and shoved 12v where it ain't supposed to go... that didn't end well  

Voltage wise the PBP is no different to a vast majority of SBCs... having 3.3v logical level IOs, with some are even lower at 1.8v, just to be awkward :O (ok, not quite, but it does make things a tad more difficult).

I've got a 3.3V TTL cable. Still no luck. Is there anything else that has to be configures? Kernel parameters or something?

[pfeerick]

Is there anything else that has to be configures? Kernel parameters or something?

Since I don't have a PBP, I can only go by the wiki info about the UART until someone who does know chimes in. But it seems the PBP also has a switch for toggling between UART and audio... have you flicked that?

UART output is enabled by flipping the UART switch to the ON position (item 9). To do so you need to remove the Pinebook Pro's bottom cover - please follow proper disassembly and reassembly protocol. The OFF position is towards the touchpad, the ON position is towards the display hinges.

With the UART switch in the ON position, console is relayed via the audiojack and the laptop's sound is turned OFF. PINE64 store sells a dedicated serial console but you can make your own if you have a serial console USB 2.0 adapter and old/ broken headphones. If you do make your own cable, please ensure that you are using a 3.3v interface (such as the CH340, FTDI-232R or PL2303 - which are often sold in 3.3v and 5v variants) to avoid damage to the CPU.

[Arwen]

@VoxUnius, Yes, you need something on the kernel command line like this;

Code:

console=ttyS2,1500000n8

The default Debian on my PBP has that kernel entry already.

And as @pfeerick said, you need to flip an internal switch;

Wiki - Pinebook Pro - Using the UART