Loic Poulain
Posts: 2
Joined: Mon Jul 31, 2017 10:28 am

ttyAMA0 / bluetooth configuration

Mon Jul 31, 2017 11:16 am

Hi there,

I works on vanilla linux/kernel to enable bluetooth over uart.
Since I don't have the schematics, wanted to know a little bit
more about the interconnect.

Today, broadcom 43438 controller rx/tx are connected to pin <32 33>.
Basically ,ttyAMA0/uart0 is configured to manage this controller (from DT).

My questions:
- Would like to enable DMA for this UART, is it supported ?
- Would like to enable hw flow control, any cts/rts rooted to the bcm chip ?
- Any other gpio/irqs (power, suspend, wakeup) ?

PhilE
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 1313
Joined: Mon Sep 29, 2014 1:07 pm
Location: Cambridge

Re: ttyAMA0 / bluetooth configuration

Tue Aug 01, 2017 6:41 pm

DMA isn't possible because the DMA controller can't do byte accesses - you end up with one data byte per word of output. I've also got a feeling that the DREQ line isn't wired up correctly.

RTS/CTS are on 16&17.

Most of the GPIO information is published. There are no dedicated power/suspend pins.

Loic Poulain
Posts: 2
Joined: Mon Jul 31, 2017 10:28 am

Re: ttyAMA0 / bluetooth configuration

Thu Aug 10, 2017 9:11 am

Thanks, this helps a lot.

What about clocking ? I see in the current DT that gpclk2_gpio43 needs to be enabled.
Is it a clock going to the BCM controller.

Regards

PhilE
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 1313
Joined: Mon Sep 29, 2014 1:07 pm
Location: Cambridge

Re: ttyAMA0 / bluetooth configuration

Thu Aug 10, 2017 10:24 am

Pi3 and Pi Zero W generate a 32KHz clock signal on GPIO43 for the WiFi+BT combo chip.

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