Help! how to use BS2p40 to control the keypad and 7-seg LEDs?
fishfish
Posts: 1
hi,
·· i am doing a project using BS2p40 to control the keypad and 5 7-segment LEDs.
·· the command is to key in the numbers and display on the LEDs.
·· we got two programs. one is to drive the keypad. one is to using 7219 to drive the LEDs to count. but we dun know how to combine them together to display the numbers which will be pressed·through the keypad.
· db VAR Bit·········· ' Debounce bit for use by keyScan.
press VAR Bit······· ' Flag to indicate keypress.
key VAR Nib········· ' Key number 0-15.
row VAR Nib········· ' Counter used in scanning keys.
cols VAR INB········ ' Input states of pins P4-P7.
' Demo loop. Waits for press to indicate a keypress, then
' displays the key on the debug screen. Note that that
' this code clears the press bit when done in order to
' prepeare for the next press.
again:
·GOSUB keyScan
·IF press = 0 THEN again
·DEBUG "key pressed = ", HEX key,CR
·press = 0
GOTO again
' ==================== KEYPAD SUBROUTINE ====================
' This code scans a 0 across the row connections of the keypad,
' then looks at the column nibble to see if that 0 has shown up
' on any of those bits. If the column bits are all 1s, then
' no key is pressed. If a column bit is 0, then a key is pressed
' at the intersection of the current row and that column.
keyScan:
FOR row = 0 TO 3······ ' Scan rows one at a time.
·LOW row·············· ' Output a 0 on current row.
·key = ~cols·········· ' Get the inverted state of column bits.
·key = NCD key········ ' Convert to bit # + 1 with NCD.
·IF key <> 0 THEN push ' No high on cols? No key pressed.
·INPUT row············ ' Disconnect output on row.
NEXT·················· ' Try the next row.
db = 0················ ' Reset the debounce bit.
RETURN················ ' Return to program.
push:
·IF db = 1 THEN done·· ' Already responded to this press, so done.
·db = 1: press = 1···· ' Set debounce and keypress flags.
·key = (key-1)+(row*4) ' Add column (0-3) to row x 4 (0,4,8,12).
' Key now contains 0-15, mapped to this arrangement:
' 0 1 2 3
' 4 5 6 7
' 8 9 10 11
' 12 13 14 15
' A lookup table is translates this to match the actual
' markings on the key caps.
·LOOKUP key,[noparse][[/noparse]1,2,3,10,4,5,6,11,7,8,9,12,14,0,15,13],key
done:
·INPUT row ' Disconnect output on row.
RETURN ' Return to program.
' Program: MAX7219.BS2
' This program controls the MAX7219 LED display driver. It demonstrates
' the basics of communicating with the 7219, and shows a convenient
' method for storing setup data in tables. To demonstrate practical
' application of the 7219, the program drives a 5-digit display to
' show the current value of a 16-bit counter (0-65535). The subroutines
' are not specialized for counting; they can display _any_ 16-bit
' value on the LCDs. (A specialized counting routine would be faster,
' since it would only update the digits necessary to maintain the
' count; however, it wouldn't be usable for displaying arbitrary
' 16-bit values, like the results of Pot, Pulsin, or an A-to-D
' conversion).
' Hardware interface with the 7219:
DATA_n con 7 ' Bits are shifted out this pin # to 7219.
CLK con 5··· ' Data valid on rising edge of this clock pin.
Load con 6·· ' Tells 7219 to transfer data to LEDs.
' Register addresses for the MAX7219. To control a given attribute
' of the display, for instance its brightness or the number shown
' in a particular digit, you write the register address followed
' by the data. For example, to set the brightness, you'd send
' 'brite' followed by a number from 0 (off) to 15 (100% bright).
decode con 9······ ' Decode register; a 1 turns on BCD decoding.
brite con 10······ ' " " " intensity register.
scan con 11······· ' " " " scan-limit register.
switch con 12····· ' " " " on/off register.
test con 15······· ' Activates test mode (all digits on, 100% bright)
' Variables used in the program.
max_dat var word··· ' Word to be sent to MAX7219.
index var nib······ ' Index into setup table.
temp var nib······· ' Temporary variable used in outputting digits.
nonZ var bit······· ' Flag used in blanking leading zeros.
dispVal var word··· ' Value to be displayed on the LEDs.
odd var index.bit0· ' Lsb of index.
' The program begins by setting up all pins to output low, matching
' the state established by the pulldown resistors.
OUTS = 0········ ' All output latches low.
DIRS = $FFFF···· ' All pins to output.
' Next, it initializes the MAX7219. A lookup table is convenient way
' to organize the setup data; each register address is paired with
' its setting data. The table sets the scan limit to 4 (5 digits,
' numbered 0-4); brightness to 3; BCD decoding to the lower 5 digits
' (the only ones we're displaying), and switches the display on. The
' MAX7219 expects data in 16-bit packets, but our lookup table holds
' a series of 8-bit values. That's why the loop below is designed to
' pulse the Load line _every_other_ byte transmitted.
for index = 0 to 7················· ' Retrieve 8 items from table.
·lookup index,[noparse][[/noparse]scan,4,brite,3,decode,$1F,switch,1],max_dat
·shiftout DATA_n,CLK,msbfirst,[noparse][[/noparse]max_dat]
·if odd = 0 then noLoad············ ' If odd is 1, pulse Load line.
·pulsout Load,1
NoLoad:···························· ' Else, don't pulse.
next······························· ' Get next item from table.
' ====================== MAIN PROGRAM LOOP ==========================
' Now that the MAX7219 is properly initialized, we're ready to send it
' data. The loop below increments a 16-bit counter and displays it on
' the LEDs connected to the MAX. Subroutines below handle the details
' of converting binary values to binary-coded decimal (BCD) digits and
' sending them to the MAX.
Loop:
·gosub MaxDisplay
·dispVal = dispVal+1
goto loop
' ========================= SUBROUTINES ============================
' The MAX7219 won't accept a number like "2742" and display it on
' the LEDs. Instead, it expects the program to send it individual
' digits preceded by their position on the display. For example,
' "2742" on a five-digit display would be expressed as:
' "digit 5: blank; digit 4: 2; digit 3: 7; digit 2: 4; digit 1: 2"
' The routine MaxDisplay below does just that, separating a value
' into individual digits and sending them to the MAX7219. If the
' lefthand digits are zero (as in a number like "102") the
' routine sends blanks, not zeros until it encounters the first
' non-zero digit. This is called "leading-zero blanking."
MaxDisplay:
nonZ = 0····························· ' Clear flag for 1st non-zero digit.
for index = 5 to 1··················· ' Work from digit 5 down to digit 1.
·shiftout DATA_n,CLK,msbfirst,[noparse][[/noparse]index] ' Send digit position.
·temp = dispVal dig (index-1)········ ' Get decimal digit (0-4) of dispVal.
·if temp = 0 then skip1·············· ' If digit = 0, don't set nonZ flag.
·nonZ = 1
skip1:
·if nonZ = 1 OR temp <> 0 OR index = 1 then skip2 ' If leading 0..
·temp = 15······································· '..write a blank to the display.
skip2:
·shiftout DATA_n,CLK,msbfirst,[noparse][[/noparse]temp]············· ' Send the digit.
·pulsout Load,5·································· ' And load the display.
next············································· ' Repeat for all 5 digits.
return··········································· ' Done? Return.
·
·· i am doing a project using BS2p40 to control the keypad and 5 7-segment LEDs.
·· the command is to key in the numbers and display on the LEDs.
·· we got two programs. one is to drive the keypad. one is to using 7219 to drive the LEDs to count. but we dun know how to combine them together to display the numbers which will be pressed·through the keypad.
· db VAR Bit·········· ' Debounce bit for use by keyScan.
press VAR Bit······· ' Flag to indicate keypress.
key VAR Nib········· ' Key number 0-15.
row VAR Nib········· ' Counter used in scanning keys.
cols VAR INB········ ' Input states of pins P4-P7.
' Demo loop. Waits for press to indicate a keypress, then
' displays the key on the debug screen. Note that that
' this code clears the press bit when done in order to
' prepeare for the next press.
again:
·GOSUB keyScan
·IF press = 0 THEN again
·DEBUG "key pressed = ", HEX key,CR
·press = 0
GOTO again
' ==================== KEYPAD SUBROUTINE ====================
' This code scans a 0 across the row connections of the keypad,
' then looks at the column nibble to see if that 0 has shown up
' on any of those bits. If the column bits are all 1s, then
' no key is pressed. If a column bit is 0, then a key is pressed
' at the intersection of the current row and that column.
keyScan:
FOR row = 0 TO 3······ ' Scan rows one at a time.
·LOW row·············· ' Output a 0 on current row.
·key = ~cols·········· ' Get the inverted state of column bits.
·key = NCD key········ ' Convert to bit # + 1 with NCD.
·IF key <> 0 THEN push ' No high on cols? No key pressed.
·INPUT row············ ' Disconnect output on row.
NEXT·················· ' Try the next row.
db = 0················ ' Reset the debounce bit.
RETURN················ ' Return to program.
push:
·IF db = 1 THEN done·· ' Already responded to this press, so done.
·db = 1: press = 1···· ' Set debounce and keypress flags.
·key = (key-1)+(row*4) ' Add column (0-3) to row x 4 (0,4,8,12).
' Key now contains 0-15, mapped to this arrangement:
' 0 1 2 3
' 4 5 6 7
' 8 9 10 11
' 12 13 14 15
' A lookup table is translates this to match the actual
' markings on the key caps.
·LOOKUP key,[noparse][[/noparse]1,2,3,10,4,5,6,11,7,8,9,12,14,0,15,13],key
done:
·INPUT row ' Disconnect output on row.
RETURN ' Return to program.
' Program: MAX7219.BS2
' This program controls the MAX7219 LED display driver. It demonstrates
' the basics of communicating with the 7219, and shows a convenient
' method for storing setup data in tables. To demonstrate practical
' application of the 7219, the program drives a 5-digit display to
' show the current value of a 16-bit counter (0-65535). The subroutines
' are not specialized for counting; they can display _any_ 16-bit
' value on the LCDs. (A specialized counting routine would be faster,
' since it would only update the digits necessary to maintain the
' count; however, it wouldn't be usable for displaying arbitrary
' 16-bit values, like the results of Pot, Pulsin, or an A-to-D
' conversion).
' Hardware interface with the 7219:
DATA_n con 7 ' Bits are shifted out this pin # to 7219.
CLK con 5··· ' Data valid on rising edge of this clock pin.
Load con 6·· ' Tells 7219 to transfer data to LEDs.
' Register addresses for the MAX7219. To control a given attribute
' of the display, for instance its brightness or the number shown
' in a particular digit, you write the register address followed
' by the data. For example, to set the brightness, you'd send
' 'brite' followed by a number from 0 (off) to 15 (100% bright).
decode con 9······ ' Decode register; a 1 turns on BCD decoding.
brite con 10······ ' " " " intensity register.
scan con 11······· ' " " " scan-limit register.
switch con 12····· ' " " " on/off register.
test con 15······· ' Activates test mode (all digits on, 100% bright)
' Variables used in the program.
max_dat var word··· ' Word to be sent to MAX7219.
index var nib······ ' Index into setup table.
temp var nib······· ' Temporary variable used in outputting digits.
nonZ var bit······· ' Flag used in blanking leading zeros.
dispVal var word··· ' Value to be displayed on the LEDs.
odd var index.bit0· ' Lsb of index.
' The program begins by setting up all pins to output low, matching
' the state established by the pulldown resistors.
OUTS = 0········ ' All output latches low.
DIRS = $FFFF···· ' All pins to output.
' Next, it initializes the MAX7219. A lookup table is convenient way
' to organize the setup data; each register address is paired with
' its setting data. The table sets the scan limit to 4 (5 digits,
' numbered 0-4); brightness to 3; BCD decoding to the lower 5 digits
' (the only ones we're displaying), and switches the display on. The
' MAX7219 expects data in 16-bit packets, but our lookup table holds
' a series of 8-bit values. That's why the loop below is designed to
' pulse the Load line _every_other_ byte transmitted.
for index = 0 to 7················· ' Retrieve 8 items from table.
·lookup index,[noparse][[/noparse]scan,4,brite,3,decode,$1F,switch,1],max_dat
·shiftout DATA_n,CLK,msbfirst,[noparse][[/noparse]max_dat]
·if odd = 0 then noLoad············ ' If odd is 1, pulse Load line.
·pulsout Load,1
NoLoad:···························· ' Else, don't pulse.
next······························· ' Get next item from table.
' ====================== MAIN PROGRAM LOOP ==========================
' Now that the MAX7219 is properly initialized, we're ready to send it
' data. The loop below increments a 16-bit counter and displays it on
' the LEDs connected to the MAX. Subroutines below handle the details
' of converting binary values to binary-coded decimal (BCD) digits and
' sending them to the MAX.
Loop:
·gosub MaxDisplay
·dispVal = dispVal+1
goto loop
' ========================= SUBROUTINES ============================
' The MAX7219 won't accept a number like "2742" and display it on
' the LEDs. Instead, it expects the program to send it individual
' digits preceded by their position on the display. For example,
' "2742" on a five-digit display would be expressed as:
' "digit 5: blank; digit 4: 2; digit 3: 7; digit 2: 4; digit 1: 2"
' The routine MaxDisplay below does just that, separating a value
' into individual digits and sending them to the MAX7219. If the
' lefthand digits are zero (as in a number like "102") the
' routine sends blanks, not zeros until it encounters the first
' non-zero digit. This is called "leading-zero blanking."
MaxDisplay:
nonZ = 0····························· ' Clear flag for 1st non-zero digit.
for index = 5 to 1··················· ' Work from digit 5 down to digit 1.
·shiftout DATA_n,CLK,msbfirst,[noparse][[/noparse]index] ' Send digit position.
·temp = dispVal dig (index-1)········ ' Get decimal digit (0-4) of dispVal.
·if temp = 0 then skip1·············· ' If digit = 0, don't set nonZ flag.
·nonZ = 1
skip1:
·if nonZ = 1 OR temp <> 0 OR index = 1 then skip2 ' If leading 0..
·temp = 15······································· '..write a blank to the display.
skip2:
·shiftout DATA_n,CLK,msbfirst,[noparse][[/noparse]temp]············· ' Send the digit.
·pulsout Load,5·································· ' And load the display.
next············································· ' Repeat for all 5 digits.
return··········································· ' Done? Return.
·
Comments
·· Well you're going to have to break this down into steps.· First get all the Variables, Constants and Pin definitions into their respective blocks at the beginning of the code.· Next you're going to have to drop all your subroutines into that section.· Then all you have to really worry about it combining the main code.
·· I am unclear as to whether or not you wrote this code, so I don't know what your programming skills are.· It looks like sample code for each device.· Have you read the "What's A Microcontroller?" tutorial on our website?· It's a free download in PDF format and will help you learn programming the BASIC Stamp.
http://www.parallax.com/detail.asp?product_id=28123
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Chris Savage
Parallax Tech Support
csavage@parallax.com