How to interface the 74HC595,and SN74HC165N chips with my BS2?
koehn29
Posts: 6
74HC595,and SN74HC165N
I need information on how to use the integrated circuts listed in the subject line.
I want to use them to add pins to my basic stamp.
Someone suggested that this was possible. Is there a pin map for these chips somewhere?
Better yet would be a detailed description on ow to set it up.
P.S. Maybe someone has already asked this question in the forum?
(How do I find it?)
I need information on how to use the integrated circuts listed in the subject line.
I want to use them to add pins to my basic stamp.
Someone suggested that this was possible. Is there a pin map for these chips somewhere?
Better yet would be a detailed description on ow to set it up.
P.S. Maybe someone has already asked this question in the forum?
(How do I find it?)
Comments
595s
http://www.parallax.com/dl/docs/books/sw/exp/sw23a.pdf
http://www.parallax.com/dl/docs/books/sw/exp/sw23b.pdf
165s
http://www.parallax.com/dl/docs/books/sw/exp/sw24a.pdf
http://www.parallax.com/dl/docs/books/sw/exp/sw24b.pdf
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DTQ
Here is another example of a message appearing on the forum WITH a perfectly good subject line, but when it appears in the email output, the subject line is COMPLETELY BLANK.
This is an ongoing problem, and in this case the reader of the email message is held clueless since the message itself makes DIRECT REFERENCE to the (missing) SUBJECT LINE!
Thanks for investigating this anomaly. If knew how to "bookmark" this message I would have reported it more appropriately in the support forum, but I've not figured out how to do that yet <sigh>.
Regards,
Bruce Bates (no smile, no wink, no grin!)<argh>
(How do I find it?)
This is why SEARCH needs to be fixed.
Rick
I rechecked my wiring against the schematic.
using this code i still do not get any high (+5V) signal on any output pin of either '595.
What's wrong?
Thanks, Ken
' ==============================================================================
'
' File...... Ex23b - 74HC595 x 2.BS2
' Purpose... Expanded outputs with 74HC595
' Author.... Parallax
' E-mail.... stamptech@parallaxinc.com
' Started...
' Updated... 01 MAY 2002
'
' {$STAMP BS2}
' {$PBASIC 2.5}
'
' ==============================================================================
'
' Program Description
'
' This program demostrates a simple method of turning three Stamp lines into
' 16 outputs with two 74HC595 shift registers. The data lines into the second
' 74HC595 is fed by the SQh output (pin 9) of the first. The clock and latch
' pins of the second 74HC595 are connected to the same pins on the first.
'
' I/O Definitions
'
·DataOut CON 0 ' serial data out (74HC595.14)
·Clock CON 1 ' shift clock (74HC595.11)
·Latch CON 2 ' output latch (74HC595.12)
'
' Constants
'
·DelayTime CON 100
'
' Variables
'
·pattern VAR Byte ' output pattern
·counter VAR Byte
· '
' Initialization
'
·Initialize:
·LOW Latch ' make output and keep low
·pattern = %00000001
'
' Program Code
'
·Go_Forward:
·counter = counter + 1 ' update counter
·GOSUB Out_595
·PAUSE DelayTime ' put pattern on 74x595
·pattern = pattern << 1 ' shift pattern to the left
·IF (pattern = %10000000) THEN Go_Reverse ' test for final position
·GOTO Go_Forward ' continue in this direction
·Go_Reverse:
·counter = counter + 1
·GOSUB Out_595
·PAUSE DelayTime
·pattern = pattern >> 1
·IF (pattern = %00000001) THEN Go_Forward
·GOTO Go_Reverse
'
' Subroutines
'
·Out_595:
·SHIFTOUT DataOut, Clock, MSBFIRST, [noparse][[/noparse]counter] ' send counter to 2nd 74HC595
·SHIFTOUT DataOut, Clock, MSBFIRST, [noparse][[/noparse]pattern] ' send pattern to 1st 74HC595
·PULSOUT Latch, 5 ' latch outputs
RETURN
The easiest fix is to update your constants:
DataOut··· CON··· 1········ ' serial data out (74HC595.14)
Clock····· CON··· 0········ ' shift clock (74HC595.11)
Latch····· CON··· 2········ ' output latch (74HC595.12)
An important lesson here is to double-check the manufacturer's data sheet for any part that you are trying to connect to.· StampWorks is due for a big update so we'll get that schematic sorted out -- sorry for the trouble my error caused you.
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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA
I've read the data sheet for Philips 74HC595 a couple of times and I must admit that like most data sheets it is somewhat indigestable for my level of understanding.·
Every time I read a data sheet I wish I had one of you really smart guys available to answer my numerous basic questions.
Chris Isaacson
So with one '595 you send 8-bits. With two '595 you send 16-bits, with three '595 you send 24 bits.
When you daisy-chain 595s the data in one can be pushed to the next by new data.· Let's say you have this setup:
· Stamp --> [noparse][[/noparse]595 #1]
[noparse][[/noparse]595 #2]
When the Stamp sends data to #1 what is currently sitting in #1 gets pushed out to #2.· What's important to understand is that the internal registers aren't transferred to the 595 pins until the latch signal is received.· This works to our advantage; if we want to refresh both devices, first we send the data for #2 (it lands in #1, but this is temporary).· Now we send the data for #1.· What was in #1 (which belongs in #2) gets moved to #2 and #1 has its own data. NOW we chan blip the latch lines and the outputs are refreshed.
I recently wrote in my column (Nuts & Volts) about the value of experimenting.· I promise that none of the explanations that you read here will match the value of an hour's worth of experimenting.· Connect LEDs to the outputs and start shifting values.· Use the DEBUG terminal to tell you what what's happening.·
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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA
I have ordered some 595s to experiment with.· I'm pretty sure I understand what you're saying but·I guess I'm not sure of the output you're trying to achieve.· This is how I see it happening each time Out_595 is called:
···· [noparse][[/noparse]595 #1]········· [noparse][[/noparse]595 #2]
·· 00000000········· 00000001······ (first time)
·· 00000001········· 00000010······ (second time)
·· 00000010········· 00000011······ (third time)
·· 00000100········· 00000100······ (fourth time)
...and so on.· Is this correct?
Chris Isaacson
·· It might be better to look at it 8 bits (1 byte) at a time...When you power up your system the 595's will be empty:
[noparse][[/noparse]595#1]·· [noparse][[/noparse]595#2]
00000000 00000000
·· Once you've shifted the first byte out, it resides in 595#1, for example, if you shiftout a value of 74, it will now be in 595#1, 595#2 will still contain zero:
[noparse][[/noparse]595#1]·· [noparse][[/noparse]595#2]
01001010 00000000
·· On the next byte shifted out, say a value of 156, it will shift into 595#1, and what was in 595#1 will shift into 595#2:
[noparse][[/noparse]595#1]·· [noparse][[/noparse]595#2]
10011100 01001010
·· Now when you shiftout your next value, say 213, it will look like this:
[noparse][[/noparse]595#1]·· [noparse][[/noparse]595#2]
11010101 10011100
·· Of course, you're probably going to want to shiftout 2 bytes at a time each time so that you are re-loading both shift registers.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
I am clear on your explanation.· I will be having fun when I receive my 595s.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
I changed my constants like you suggested, Jon, but alas... still nothing
my Chips are numbered 74HC595N. On the data sheet it says that the "N" variant (MM74HC595N) is a (PDIP) not an (SOIC).
Would this make a difference?
Ssshh... (I got these from parralax) If I have the right hardware, And I have it connected properly it would be working!
I am reasonably sure (beyond the shadow of a doubt!) that I have it connected exactly according to the schematic.
I have double checked my code, and all is in place. I bought 2 chips and both do absolutely nothing!
So help me Anyone!!
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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA