Strange problem with serial out on my project...

Chris_D

Hey guys,

I am stumped. I am working with a propeller chip - it has been working good for
several days communicating with a keyboard, mouse, my AVR, and producing VGA
display output.· This is all on my own circuit board

Sometime this afternoon, suddenly it was no longer outputting data to my AVR via
serial 57600 baud. I can send data to it and it receives it fine and displays
the proper information on the VGA display.

Seeing as I have not been programming the prop, I don't think the software changed so I
assumed it was something on my AVR. However, I put my scope on the transmit
signal from the PROPELLER and noticed I am getting a fairly consistant square
wave. My scopes knobs are a bit "testy", but I believe the signal I am seeing
is .2msecs off and .4 msecs ON. During this, it should not be transmitting
anything. It should only be transmitting during a keypress or mouse click.

I also used my VOM's frequency measurement function and it is showing a
frequency of 1.64 Khz.

What the heck could be causing this?

Chris

Peter Jakacki

no circuit, no code, no idea

*Peter*

Chris_D

I am wondering is somehow the clock signal for either the mouse or the keyboard isn't getting messed up with the serial TX line?· I can't think of any other way to get a consistant square wave pattern on the TX line.

The schematics are identical to the Demo board schematics - from which I built this circuit board.

Here is the source code

**************************************************************************************

'Riam-VGA Display Interface
'4/29/09 - modified to run on RIAM board
'tested baud at 115200 - missing lots of characters, went back to 57600
'added logic to blink LEDs for Keyboard, Mouse, & video feed

CON
· _clkmode = xtal1 + pll16x
· _xinfreq = 5_000_000
· cols = vgatext#cols
· rows = vgatext#rows
· chrs = cols * rows

OBJ
· vgatext : "vga_hires_text"
· mouse·· : "mouse"
· SerIO·· : "FullDuplexSerial"·············· 'Serial communications object
·· kb : "keyboard"
VAR
· 'sync long - written to -1 by VGA driver after each screen refresh
· long· sync
· 'screen buffer - could be bytes, but longs allow more efficient scrolling
· byte· screen[noparse][[/noparse]cols*rows]
· 'row colors
· word· colors[noparse][[/noparse]rows]
· 'cursor control bytes
· byte· cx0, cy0, cm0, cx1, cy1, cm1
· Byte DispCmd······· 'Command for video display
····················· '1 show text
· Long DispX········· 'Column position of text to show
· Long DispY········· 'Row position of text to show
· Byte DispText[noparse][[/noparse]100]· 'ASCII codes of text to show
· Byte Mcu_Status
· Byte Temp
· Long TempL
· Long Index1
· Long Index2
· word At_Key
· byte Special_Code
· Long Prev_M_X
· Long Prev_M_Y
· Long Current_M_X
· Long Current_M_Y
· Long M_Prev_LeftB
· Long M_Current_LeftB
· Byte Mouse_Down
· Byte Mouse_Up
· Byte Active_Editor
······· '0 = none
······· '1 = CNC editor
······· '2 = sub screen editor
· Byte Min_Line_Len
· Byte Max_Line_Len
·
PUB start | i, j, k
· 'start vga text driver
· vgatext.start(16, @screen, @colors, @cx0, @sync)
·· 'start the keyboard
· kb.start(26, 27)
· 'echo keystrokes in hex
·' repeat
·· ' term.hexd(kb.getkey,3)
'··· Term.dec(kb.getkey)'
'·· term.out(" ")

· 'start mouse and set bound parameters
· mouse.start(24, 25)
· mouse.bound_limits(0, 0, 0, cols - 1, rows - 1, 0)
· mouse.bound_scales(2, -3, 0)
'· SerIO.start(7, 6, 0, 38400)
· SerIO.start(31, 30, 0, 57600)
· 'Rx pin is 31
· 'Tx pin is 30
· 'Set LEDs as outputs
· Dira[noparse][[/noparse]10]~~··················· 'Keyboard
· Dira[noparse][[/noparse]11]~~··················· 'Mouse
· Dira[noparse][[/noparse]12]~~··················· 'Video
·
·'set up colors
· repeat i from 0 to 19
··· colors[noparse][[/noparse]i] := %%3330_0030
· repeat i from 20 to rows - 3
···· colors[noparse][[/noparse]i] := %%3330_0000
···
· colors[noparse][[/noparse]48] := %%3330_3000
· colors[noparse][[/noparse]49] := %%3330_3000
·
· 'fill screen with characters
· repeat i from 0 to chrs - 1
··· k := k + 1
··· screen.byte[noparse][[/noparse]i] := 32' // $81
··· if k == 100
······ k:= 0
· Repeat i from 4800 to 4899
··· Screen.byte[noparse][[/noparse]i] := 14 // $81
·
· 'set cursor 0 to be a solid block
· cm0 := %001
· 'set cursor 1 to be a blinking underscore
· cm1 := %111
· M_Prev_LeftB := 0
· Mouse_Down := 1
· Mouse_Up := 2
· Mcu_Status := 0
· cx1 := 0
· cy1 := 49


· repeat
··· at_Key := kb.key
··· SerIO.tx(at_Key)
····· if at_Key <> 0
······· !outa[noparse][[/noparse]10]

···· DispCmd := 0
···· DispCmd := SerIO.rxtime(5)
···· Case DispCmd
······· 27:············································ 'Escape key sequence - special operation
·········· Special_Code := SerIO.rxtime(5)
·········· case Special_Code
············ 1:······································ 'Clear screen
················ repeat i from 0 to chrs - 1
···················· screen.byte[noparse][[/noparse]i] := 32
············ 100:······································ 'place cursor at program line editor
················ cx1 := 0
················ cy1 := 20
················ Active_Editor := 1
················ Min_Line_Len := 0
················ Max_Line_Len := 74
············ 101:······································ 'place cursor at second screen editor
················ cx1 := 76
················ cy1 := 20
················ Active_Editor := 2
················ Min_Line_Len := 76
················ Max_Line_Len := 99
············ 102:······································ 'place cursor at abs x position
················ Special_Code := SerIO.rxtime(5)
················ cx1 := Special_Code
················ cy1 := 20
············ 103:······································ 'place cursor on status line
················ cx1 := 1
················ cy1 := 49
······· 10:
·········· !outa[noparse][[/noparse]12]
·········· Fetch_Long(@DispX)
·········· Fetch_Long(@DispY)
·········· Index1 := ((DispY * 100)+DispX)
·········· Index2 := 0
·········· Repeat
············ Temp := SerIO.rx'time(1)
············ if Temp > 0
··············· screen[noparse][[/noparse]Index1] := Temp
··············· index1 := index1 + 1
··············· SerIO.tx(Mcu_Status)
·········· while Temp > 0
·········· DispCmd := 0
·········· SerIO.tx(Mcu_Status)
······· 223:··········································· 'pause break key - only temporary for clear screen testing
·········· repeat i from 0 to chrs - 1
············ screen.byte[noparse][[/noparse]i] := 32
······· 193:
········· if cx1 < Max_Line_Len
············ cx1 := cx1 + 1
········· cy1 := 20
······· 192:
········· if cx1 > Min_Line_Len
············ cx1 := cx1 - 1
········· cy1 := 20

· 'main loop - mouse controls stuff
··· cx0 := mouse.bound_x····· 'cursor 0 follows mouse
··· cy0 := mouse.bound_y
··· if mouse.button(0)······· 'if left-click, cursor 1 moves to mouse
····· !outa[noparse][[/noparse]11]
····· repeat while mouse.button(0) 'clears out buffer so multiple 'clicks' are not passed through
····· Current_M_X := mouse.bound_x
····· Current_M_Y := mouse.bound_y
····· SerIO.Tx(Mouse_Down)
····· SerIO.Tx(Current_M_X)
····· SerIO.Tx(Current_M_Y)
PRI Fetch_Long(LongToFetch)| LocalByte,local_long
····· LocalByte := SerIO.Rx
····· local_long.byte[noparse][[/noparse]0] := LocalByte
····· LocalByte := SerIO.Rx
····· local_long.byte[noparse][[/noparse]1] := LocalByte
····· LocalByte := SerIO.Rx
····· local_long.byte[noparse][[/noparse]2] := LocalByte
····· LocalByte := SerIO.Rx
····· local_long.byte[noparse][[/noparse]3] := LocalByte
····· LONG[noparse][[/noparse]LongToFetch] := Local_Long
····· Return
·
PRI Xmit_Long(LongToSend)| LocalByte
····· LocalByte := LongToSend.byte[noparse][[/noparse]0]
····· SerIO.tx(LocalByte)
····· LocalByte := LongToSend.byte[noparse][[/noparse]1]
····· SerIO.tx(LocalByte)
····· LocalByte := LongToSend.byte[noparse][[/noparse]2]
····· SerIO.tx(LocalByte)
····· LocalByte := LongToSend.byte[noparse][[/noparse]3]
····· SerIO.tx(LocalByte)
····· return













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Timmoore

kb.key returns 0 if no char typed. This will send $00 on serial port, at 56700 board the 0 will be ~0.2ms. You may simply be seeing the $00 being sent each time round the loop.

Chris_D

Tim,

I suspect you are right.· That helps me to narrow this down further.· I will dissable the keyboard function to get closer to the source of the problem.



Thanks



Chris

Chris_D

GRRR, intermittent problems are enough to make my hair fall out faster than normal.· This morning it is working fine and dandy.



Thanks for the help guys.



Chris

kwinn

This may be a stuck key on the keyboard.