Pi 3 Bluetooth simple

Hello,

Bluetooth for RISC OS was already discussed here but always as a full Bluetooth stack supporting Bluetooth devices like keyboard etc. This could be indeed some work.

But there may be a more simple approach and still useful: use of the Pi 3 CYW43438 as a Bluetooth-UART-bridge. In this way wireless serial commmunication could be established between two Pi 3: one could do some embedded measurements and the other displaying it on the desktop.

The CYW43438 Bluetooth is connected to UART0 this is completely independent of the CYW43438 WLAN SDIO. Furthermore, different to Bluetooth-USB-dongles usage of USB stack is not needed.

There is already a bare-metal project (not from me) for CYW43438 Bluetooth UART0. The question is: would it be better to implement Bluetooth-UART-bridge bare-metal first and then integrate into RISC OS?

https://github.com/rsta2/circle
https://github.com/rsta2/circle/blob/master/sample/22-btsimple/README

“You need a Raspberry Pi 3 (with internal Bluetooth device) or an external USB Bluetooth BR/EDR dongle to use this sample”

Thanks
Lothar

Hi,

Did you already working on this. Would we then put Bluetooth in the HAL or put as device driver ?.

I did some initial work but currently need to work on other things e.g. Pi Zero W GPIO support and AUTOEXEC for embeddded applications.

The problem with CYW43438 Bluetooth is I found the documentation quite poor and many things are just trial and error. This has a “simple” UART interface so should be easy in comparison to a Bluetooth USB dongle – but not so much.

On the other hand what already works without problems is Pi 2 BCM2837 and external HC-05/06 Bluetooth with UART interface. But certainly it would be nice to do the same with Pi 3 BCM2837 and “internal” CYW43438 Bluetooth.

Is the HC-05/06 already supported in RISC-OS ?. I was under impression that there was no Bluetooth support in RISC-OS at all. I have come to the conclusion that for Bluetooth the HAL is not the place. It will be more of a module. And as usual the documentation is poor. But hey the Pi is not open source it is more open learning ;-)

> Is the HC-05/06 already supported in RISC-OS

There is no need these are configured by a serial terminal similar to here or in a BASIC program using serial module and then work as a wireless null modem between two Pi e.g. Pi 2 UART0 and Pi 3 UART1

https://www.riscosopen.org/news/articles/2016/04/06/get-connected-with-rool

> CYW43438 Bluetooth

This is internally connected to Pi 3 UART0 but how to do initial configuration is what is still needed.

Did you already start with some code ?.

I understand you started working on Pi 3 UART0 using the HAL. Did you have any success? For me the recommended ROM OS_SerialOp does nothing:

https://www.riscosopen.org/forum/forums/9/topics/6347

The Serial Block Drivers work but the programming examples do not work properly:

https://www.riscosopen.org/forum/forums/11/topics/9368

Nevertheless with !Connector you can configure a Bluetooth module. However for Bluetooth communication from a program – with ROM OS_SerialOp not working – what I did now is operate the UART0 directly: bypassing the HAL. The attached code sends out a string. But if you do have success with the HAL please let me know. It would be much better if the ROM OS_SerialOp would work. Then I would think the best way to implement Bluetooth communication is a BASIC module to do some SWIs for it.

UART0_DR     = &00
UART0_FR     = &18
UART0_IBRD   = &24
UART0_FBRD   = &28
UART0_LCRH   = &2C
UART0_CR     = &30
UART0_IMSC   = &38
UART0_ICR    = &44

DIM CODE% (&100)
P% = CODE%
[
.uart0base
  EQUD  &3F201000  ; UART0 base address on Pi 3
.uart0logical
  EQUD  &00000000

.init_memory
  ; protected memory access
  MOV   R0, #&0D         ; physical to logical address map (permanent)
  LDR   R1, uart0base    ; physical address
  MOV   R2, #&100        ; logical address space size 256 bytes
  SWI   "OS_Memory"      ; MMU
  ADR   R0, uart0logical
  STR   R3, [R0]         ; returned logical address pointer
  MOV   PC, LR           ; return

.init_uart0
  SWI   "OS_EnterOS"       ; supervisor mode
  ADR   R11, uart0logical
  LDR   R11, [R11]         ; logical address pointer

  ; Disable UART0
  MOV   R0, #0
  STR   R0, [R11, #UART0_CR]

  ; Clear pending interrupts
  ; UART0_ICR = 0x7FF
  MOV   R0, #&800
  SUB   R0, R0, #1
  STR   R0, [R11, #UART0_ICR]

  ; Set integer & fractional part of baud rate
  ; Divider = UART_CLOCK/(16 * Baud)
  ; Fraction part register = (Fractional part * 64) + 0.5
  ; UART_CLOCK = 3000000; Baud = 115200
  ; Divider = 3000000 / (16 * 115200) = 1.627 = 1
  ; Fractional part register = (.627 * 64) + 0.5 = 40.6 = 40
  MOV   R0, #1
  STR   R0, [R11, #UART0_IBRD]
  MOV   R0, #40
  STR   R0, [R11, #UART0_FBRD]

  ; Enable FIFO & 8 bit data transmissio (1 stop bit, no parity)
  ; UART0_LCRH = (1 << 4) | (1 << 5) | (1 << 6)
  MOV   R0, #%01110000
  STR   R0, [R11, #UART0_LCRH]

  ; Mask all interrupts
  ; UART0_IMSC = (1 << 1) | (1 << 4) | (1 << 5) | (1 << 6) |
  ;              (1 << 7) | (1 << 8) | (1 << 9) | (1 << 10)
  MOV   R0, #(%00000111<<8)
  ADD   R0, R0, #%11110010
  STR   R0, [R11, #UART0_IMSC]

  ; Enable UART0 receive & transfer
  ; UART0_CR = (1 << 0) | (1 << 8) | (1 << 9)
  MOV   R0, #((1<<9)+(1<<8))
  ADD   R0, R0, #(1<<0)
  STR   R0, [R11, #UART0_CR]

  SWI   "OS_LeaveOS"  ; user mode
  MOV   PC, LR        ; return

.uart0_send
  ; parameter from BASIC
  LDR   R1, [R9]           ; load first parameter address
  LDR   R0, [R1]           ; load first parameter val1%

  SWI   "OS_EnterOS"       ; supervisor mode
  ADR   R11, uart0logical
  LDR   R11, [R11]         ; logical address pointer

  ; Wait for UART0 ready to transmit
  ; while  UART0_FR & (1 << 5)

.uart0_send_loop
  MOV   R1, #(1<<5)
  LDR   R2, [R11, #UART0_FR]
  TSTS  R2, R1
  BNE   uart0_send_loop

  STR   R0, [R11, #UART0_DR]

  SWI   "OS_LeaveOS"  ; user mode
  MOV   PC, LR        ; return
]

CALL init_memory
CALL init_uart0

REPEAT
  val1% = ASC("T")
  CALL uart0_send, val1%
  val1% = ASC("E")
  CALL uart0_send, val1%
  val1% = ASC("S")
  CALL uart0_send, val1%
  val1% = ASC("T")
  CALL uart0_send, val1%
  val1% = &0D
  CALL uart0_send, val1%

  REMARK : delay
  timeact = TIME + 40
  REPEAT
  UNTIL TIME > timeact
UNTIL FALSE

> The Serial Block Drivers work but the programming examples do not work properly

Got it working. Now I only need to find out: is COM 0 now UART0 or UART1 on the Pi 3

https://www.riscosopen.org/forum/forums/11/topics/9368

Made a start of writing the module in C with the toolkit. So the work has started. However this is the first module in C so bare with me. I did choose C because it is more readable then Assembler. If the module works I will have a look to have in the HAL ( Or not ;-)).

However this is the first module in C so bare with me.

Very small point of English language use:
Bare = naked, unclothed, unadornished
Bear = “take a burden”, “take a load”, or in this instance “be patient”

Bare = naked, unclothed, unadornished
Bear = “take a burden”, “take a load”, or in this instance “be patient”

I know you’re a cat person, Steve, but this lunchtime, after French class. the dog went for a quick run on a small patch of beach, and cavorted merrily. Wife said “he likes the sand under his bare feet – paws”:

I responded “His bear paws!”, as his paws do indeed resemble those of a bear (his claws need trimming!)!

No more relevant to the topic, but somehow fitted in!

Bear paws – it’d be an odd dog whose paws resembled those of a bear. Here’s a bear paw print in the sand by the river at the edge of my in-laws’ farm:

https://www.facebook.com/photo.php?fbid=10151384842367762

Bare – small fur-less (except patches, mostly at the top) humanoid shaped life form usually found in a non-bare state due to a female variant being tempted by a snake (it’s a long story).

Bear – somewhat larger furry humanoid shaped life form well known for defecating in wooded areas. For some reason not clearly understood, the fur-less humanoids from the left side of the planet appear to have an obsession with bear arms, though anybody who has ever fought a bear and survived (Chuck Norris, Russian presidents…) might tell you that their legs and teeth are just as deadly…

I’m looking forward to seeing the fruits of your efforts, Timo!

Bare – small fur-less …

Sometimes you wish you hadn’t…
but yes English has many homonyms

I have no wish to distract Timo from a worthy item of work because of a trivial twist in spoken/written English that really needs any discussion to continue in Aldershot.

Yes I do apologize my English writing is horrible.

Yes I do apologize my English writing is horrible.

Actually, no it isn’t. It’s actually better than people I know who were born here.

Actually, no it isn’t. It’s actually better than people I know who were born here.

I’ll second that. And far, far better than our second languages, those of us who have any at all.

So last evening during the evening of the Big Ben Club in Delft ( The Netherlands ) I continued work on the module for the Mini UART for the RPi. Searched and found some interesting source code and made some progress. Yes better copy ( if allowed ) good developed source code then write yourself bad code. Interesting enough the Mini UART is very close to the SPI so perhaps make one good header file for it.

@Lothar:

Slowly comming there. Although it is written in C