Serial output - Is there a better way to do this?

Jeff Haas · 2015-10-18 00:15

I'm learning Spin having moved over from PBasic, and I've got one of the inexpensive Catalex MP3 players mentioned in another thread. It works fine with this code:

{
 Catalex mp3 board sound test
 10/17/2015
 One MP3 in a folder named 01 on MicroSD card.  
}
CON
   
  _clkmode = xtal1 + pll16x         ' Crystal and PLL settings.
  _xinfreq = 5_000_000              ' 5 MHz crystal x 16 = 80 MHz

OBJ

  Serial : "FullDuplexSerial" 

PUB Go                                

  serial.start(2, 3, %0000, 9_600)

  Serial.Tx($7E)                  ' Init the Catalex MP3 player
  Serial.Tx($FF)
  Serial.Tx($06)
  Serial.Tx($0C)
  Serial.Tx($00)
  Serial.Tx($00)
  Serial.Tx($00)
  Serial.Tx($EF)
    
  waitcnt(clkfreq + cnt)            ' Wait 1 second
  waitcnt(clkfreq + cnt)            ' Wait 1 second
  
  Serial.Tx($7E)                  ' Select TF socket
  Serial.Tx($FF)
  Serial.Tx($06)
  Serial.Tx($09)
  Serial.Tx($00)
  Serial.Tx($00)
  Serial.Tx($02)
  Serial.Tx($EF)
  
  waitcnt(clkfreq + cnt)            ' Wait 1 second
  
  Serial.Tx($7E)                    ' Set volume to 15
  Serial.Tx($FF)
  Serial.Tx($06)
  Serial.Tx($06)
  Serial.Tx($00)
  Serial.Tx($00)
  Serial.Tx($0F)
  Serial.Tx($EF)
  
  waitcnt(clkfreq + cnt)            ' Wait 1 second  

  Serial.Tx($7E)                    ' Play song 1 in folder 1
  Serial.Tx($FF)
  Serial.Tx($06)
  Serial.Tx($0F)
  Serial.Tx($00)
  Serial.Tx($01)
  Serial.Tx($01)
  Serial.Tx($EF)

However, I can't figure out how to represent all the serial commands on a single line. It's easy on the BS2:

SEROUT MP3, 84, [$7E,$FF,$06,$09,$00,$00,$02,$EF]   'Select TF socket

What's the best way to do this? I tried out the other commands in FullDuplexSerial but couldn't get them to work. And I've looked through lots of the other serial methods in the OBEX but can't find what I want.

Ariba · 2015-10-18 01:31

The str methode with a string() pseudo function does something like that, but it can not handle $00 values, because these signals the end of the string.

One way to do it is with byte arrays in a DAT section:

PUB Go
  ...
  CatalexCmd(@MP3Init)
  CatalexCmd(@Volume)    'set volume to 15
  ...
  Volume[6] := 3
  CatalexCmd(@Volume)    'set volume to 3


PRI CatalexCmd(pntr) : i
  repeat i from 0 to 7
    Serial.Tx(byte[pntr][i])

DAT
MP3Init   byte  $7E,$FF,$06,$0C,$00,$00,$00,$EF
Volume    byte  $7E,$FF,$06,$06,$00,$00,$0F,$EF

As you see, you can also modify the byte data very easy before you send a command.

Andy

Jeff Haas · 2015-10-18 07:23

Andy,

Thanks! That was just what I needed. I'm still getting my head around the whole object and method-oriented way of doing things.

FYI, after some experimentation, for anyone else interested in using the Catalex board, the MP3Init sequence is not needed. You just need these:

DAT

SelectTF      byte $7E,$FF,$06,$09,$00,$00,$02,$EF  'Select TF socket on Catalex
Volume        byte $7E,$FF,$06,$06,$00,$00,$0F,$EF  'Set volume to 15
PlayMP3       byte $7E,$FF,$06,$0F,$00,$01,$01,$EF  'Play song 1 in folder 1

Then you can select both the MP3 to play and the folder using these commands, as Andy shows above:

PlayMP3[5] := 2          'Select SD card folder      
PlayMP3[6] := 1          'Select mp3 in folder

Jeff

JonnyMac · 2015-10-18 14:08

Piggy-backing on Andy's examples, I would suggest creating simple method calls so that you only have to look into the details of the device once. For example:

pub set_volume(v)

  Volume[6] := 0 #> v <# MAX_VOL
  CatalexCmd(@Volume)

Shawn Lowe · 2015-10-18 15:30

Jeff Haas wrote: »

I'm learning Spin having moved over from PBasic, and I've got one of the inexpensive Catalex MP3 players mentioned in another thread. It works fine with this code:

{
 Catalex mp3 board sound test
 10/17/2015
 One MP3 in a folder named 01 on MicroSD card.  
}
CON
   
  _clkmode = xtal1 + pll16x         ' Crystal and PLL settings.
  _xinfreq = 5_000_000              ' 5 MHz crystal x 16 = 80 MHz

OBJ

  Serial : "FullDuplexSerial" 

PUB Go                                

  serial.start(2, 3, %0000, 9_600)

  Serial.Tx($7E)                  ' Init the Catalex MP3 player
  Serial.Tx($FF)
  Serial.Tx($06)
  Serial.Tx($0C)
  Serial.Tx($00)
  Serial.Tx($00)
  Serial.Tx($00)
  Serial.Tx($EF)
    
  waitcnt(clkfreq + cnt)            ' Wait 1 second
  waitcnt(clkfreq + cnt)            ' Wait 1 second
  
  Serial.Tx($7E)                  ' Select TF socket
  Serial.Tx($FF)
  Serial.Tx($06)
  Serial.Tx($09)
  Serial.Tx($00)
  Serial.Tx($00)
  Serial.Tx($02)
  Serial.Tx($EF)
  
  waitcnt(clkfreq + cnt)            ' Wait 1 second
  
  Serial.Tx($7E)                    ' Set volume to 15
  Serial.Tx($FF)
  Serial.Tx($06)
  Serial.Tx($06)
  Serial.Tx($00)
  Serial.Tx($00)
  Serial.Tx($0F)
  Serial.Tx($EF)
  
  waitcnt(clkfreq + cnt)            ' Wait 1 second  

  Serial.Tx($7E)                    ' Play song 1 in folder 1
  Serial.Tx($FF)
  Serial.Tx($06)
  Serial.Tx($0F)
  Serial.Tx($00)
  Serial.Tx($01)
  Serial.Tx($01)
  Serial.Tx($EF)

However, I can't figure out how to represent all the serial commands on a single line. It's easy on the BS2:

SEROUT MP3, 84, [$7E,$FF,$06,$09,$00,$00,$02,$EF]   'Select TF socket

What's the best way to do this? I tried out the other commands in FullDuplexSerial but couldn't get them to work. And I've looked through lots of the other serial methods in the OBEX but can't find what I want.

which thread are you referring? Just curious

Publison · 2015-10-18 15:34

Shawn Lowe wrote: »

which thread are you referring? Just curious

Could be this one:

http://forums.parallax.com/discussion/161245/erco-here-s-the-cheap-mp3-modules

JonnyMac · 2015-10-18 16:01

After looking at the docs I knocked up a little object for that player. I don't tend to post untested code (I don't have a player yet), but I'm confident this should be safe to try.

Since I don't have one and I wanted others to be able to reference the Schmarschmino demos the vendor provides, I used their named constants. Once I get a player and understand what each thing does, I may rename things. Note, too, that all of the demos show no feedback from the player and a baud rate of 9600. This can be done with a single pin and a method; no serial cog is required.

Mike Green · 2015-10-18 16:19

It's pretty easy to create a routine that works like STR but allows for a zero byte:

PUB txStrEsc(str) | temp
  repeat while temp := BYTE[ str++ ]  ' repeat as long as byte isn't zero
    if temp == $7F  ' escape byte is $7F
      if (temp := BYTE[ str++ ]) => $80  ' get escaped byte value
        Serial.Tx(temp & $7F)  ' strip high order bit for transmission
      else  ' A $7F must not be followed by a byte less than $80
        quit  ' This is so a string ending with $7F will terminate properly
    else
      Serial.Tx(temp)

To transmit the example shown for the BS2, do:

txStrEsc( string( $7E, $FF, $06, $09, $7F, $80, $7F, $80, $02, $EF ) )

A $7F is followed by the byte to be sent with its high order bit set. To send $00, use $7F,$80. To send $7F, use $7F,$FF. There's a check for the case where a $7F is the last byte in a string.

Tracy Allen · 2015-10-18 17:40

For this common situation add a method to your serial object. Enter with a pointer to the string and the count of bytes.

PUB StrN(stringptr,nchar)
'' Send counted string
  repeat nchar
    tx(byte[stringptr++])

Then as Jon suggests, in the application give each function a meaningful name that calls the generic StrN. Or, simply give each string a name that reveals its function.

Tracy Allen · 2015-10-18 18:14

Actually, looking at Jon's program, I see that the device command set has several constant elements and two variable elements, and Jon has encapsulated that in a method,

send_command(cmd, value)

Very much on target, as usual.

JonnyMac · 2015-10-18 19:02

To be fair, I simply ported code from the vendor's Schmarschmino demo. Here's the original.

void sendCommand(int8_t command, int16_t dat)
{
  delay(20);
  Send_buf[0] = 0x7e; //
  Send_buf[1] = 0xff; //
  Send_buf[2] = 0x06; //
  Send_buf[3] = command; //
  Send_buf[4] = 0x00;//
  Send_buf[5] = (int8_t)(dat >> 8);//datah
  Send_buf[6] = (int8_t)(dat); //datal
  Send_buf[7] = 0xef; //
  for(uint8_t i=0; i<8; i++)//
  {
    mySerial.write(Send_buf[i]) ;
  }
}

I didn't think it was necessary to stick the bytes into a buffer before sending -- at 9600 baud a few microseconds here and there between bytes should be fine.

pri send_command(cmd, value)

  delay(20)
  tx($7E)
  tx($FF)
  tx($06)
  tx(cmd)
  tx($00)
  tx(value.byte[1])
  tx(value.byte[0])
  tx($EF)


pri delay(ms) | t

  t := cnt
  repeat ms
    waitcnt(t += clkfreq/1000)


pri tx(b) | t                                           ' borrowed from Simple Serial

'' True mode output of byte b

  b := (b | $FF00) << 2                                 ' add stop bit(s), start bit

  t := cnt                                              ' sync bit timer
  repeat 10                                             ' start + 8 bits + stop
    waitcnt(t += bitticks)                              ' hold for bit timing
    outa[txp] := b >>= 1                                ' output next bit

That demo commands disable response from the device so I kept it to one pin. Since coms is the very tame speed of 9600 baud, I was able to borrow (with some clean-up) serial output from Simple Serial.

Jeff Haas · 2015-10-21 07:28

I tried out JonnyMac's port of the C code, by using jm_debounce to read the buttons and then send commands to jm_catalex_mp3. It works!

I set up six buttons as the schematic in the original file here in the OBEX shows. Those aren't shown below because some characters don't display properly in the forum.

'' =================================================================================================
''
''   File....... jm_debounce_catalex_mp3.spin
''   Purpose.... Debounces inputs, sends commands to Catalex MP3 player
''   Updated.... 20 OCT 2015
''
'' =================================================================================================

con

  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000 


con

  BTN_UP   = %000001 << 18                                       ' for JM LCD UI board 
  BTN_DN   = %000010 << 18
  BTN_LF   = %000100 << 18
  BTN_RT   = %001000 << 18
  BTN_OK   = %010000 << 18
  BTN_ESC  = %100000 << 18

  BTN_MASK = BTN_UP | BTN_DN | BTN_RT | BTN_LF | BTN_OK | BTN_ESC

  ACT_HI   = 1
  ACT_LO   = 0 


obj

  btns : "jm_debounce"
  catalex  : "jm_catalex_mp3"

var


pub main | b

  catalex.setup(3)                            ' TX pin to Catalex is pin 3  
    
  btns.init(BTN_MASK, 25, ACT_HI)

  repeat
    if btns.getbits(BTN_ESC)
      catalex.stop

    b := btns.getbits(BTN_MASK) & !BTN_ESC                      ' all but Esc
    case b
      BTN_UP : catalex.play_from_folder(2,1)               ' LCD commands in original replaced with these commands for testing
      BTN_DN : catalex.next_song 
      BTN_LF : catalex.previous_song
      BTN_RT : catalex.volume_up
      BTN_OK : catalex.volume_down 
    

    waitcnt(clkfreq / 10 + cnt)

Serial output - Is there a better way to do this?

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