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BS2P40, OEM — Parallax Forums

BS2P40, OEM

hmlittle59hmlittle59 Posts: 404
in BASIC Stamp
Hello All,
After a few jumper wire's, trace cuts, and re-order of the correct size parts, my latest version of my 4 x 3 PCB has been up and running for 2 1/2 mths. The original software (5 yrs ago) is almost converted to the new layout with dual (Serial & Parallel LCD Screen) both actively displaying the same data added (Thanks Chris & Hal). One DLST short cut to save space in 2 FULL slots was completed while on vacation last week......OK GREAT!!!
AT ISSUE:
Our Son came by before us and said that he stopped a beeping sound that was coming from my Unit Under Test (UUT). Closed the Magnetic Switch. I didn't think much of it at the time.
PROBLEM:
When I finally checked my OEM, the Serial LCD was blank but the Parallel Screen has all the data and is working (the board drives both Displays at the same time). The over all board appears to be working. But after several reboots and replacement of the Serial LCD, it is still blank. The I/O pin is connected directly to the Video pin. Voltage is good.
During Alarm the program turns the Back light 'ON' (more current draw). (I must have bumped the Magnetic Switch before leaving on vacation)

Question:
Can the (#BS2P40) handle the current draw from a Serial LCD with Backlight constantly on? It worked great for short periods of time, but it could of been on for 7 days constantly this time. I'm trying to find the I/O pin rating and have not found it yet.

1) Trying to find (#BS2P40) I/O pin rating. (maybe I just missed it...thanks)
2) Serial LCD Backlight 'ON', is (80ma)

PS: Will try and splice in an extra I/O pin for a temporary fix for now.....Good Data in the long run though.

Thanks again for any help.

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    When you ask if the BS2p40 can handle the current draw from a serial LCD with a backlight on, where is the LCD getting its power from? That makes a huge difference. Generally the LCD would get power from the same place as the BS2P40, however if you're getting it from the VDD of a BS2P40 module then you might just be exceeding the current the on-board regulator can provide. If you're getting it from an I/O pin you're definitely exceeding that rating.
  • hmlittle59hmlittle59 Posts: 404
    I'm using a Wall Adapter 120 to 9 VDC, through a 2 amp 5 v regulator. Both LCD's and #PBASIC48W_P40 Interpreter chip are coming off the same regulator. All voltages are good all over the board and the Parallel LCD is still working.
    All data to both LCD's was working great. Showing everything clear on the Serial LCD.
    I must have bumped the Mag. Switch when shutting down the computer before vacation and there is a 10 min. delay before the Piezo would have sounded (alerting me) with the Backlight 'ON' and we were already gone.
    I did find the spec. of the Interpreter Chip on the 40 pin Module Controller. I've learned (from here) that the Parallel Display's Back Light (LED) is totally separate from the LCD's voltage, but does the Serial LCD operate the same way?
    1) Meaning, if the Back Light is 'ON', is there any increase Current draw from the 'V' pin of the Serial Display?
    2) Do you think that a 220 ohm resistor would helped if I find that the Interpreter I/O pin is dead? (would be added on the next spin)

    thanks for any help
    PS: will Scope and splice/ jumper in extra I/O pin and tomorrow.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    hmlittle59 wrote: »
    1) Meaning, if the Back Light is 'ON', is there any increase Current draw from the 'V' pin of the Serial Display?

    Where is the 'V' pin on the serial display?

    On the Parallax Serial Display, there are 3 pins. GND, 5V and RX. The amount of current the 5V draws varies greatly depending on whether the backlight is on or not.

  • hmlittle59hmlittle59 Posts: 404
    I was meaning the 'V' video pin (RX). I see that you wrote on the 5V line. House duties today, hope to jumper board tomorrow.

    Thanks for the info
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    hmlittle59 wrote: »
    I was meaning the 'V' video pin (RX).

    A serial LCD with a video pin...yeah, that can't be one of ours. ;)

  • hmlittle59hmlittle59 Posts: 404
    Hello All,
    Up-Date:
    Software 98% done. Two of 8 slots 97% full and flowing well. Got the new PCB's in with corrected layout, "BUT".
    I clicked on "Identify" from the Editor first and that came back with the proper Interpreter information (GREAT). But when I clicked "RUN" to download the code I get "Hardware Communication Error", I've never had that problem before. Did a search on the forum and could not find anything related.
    Did go back and check my first OEM PCB and everything still working.
    Any feedback or thoughts? Will start with my 104 CAPs and make sure they were not mixed up from my bin.

    Problem:
    1) "Hardware Communication Error"....never had this error before...1st PCB still works

    "Identify" works....
    Howard
  • hmlittle59hmlittle59 Posts: 404
    Up-Date:
    Changed input communication Caps. 0.1uF NO change. Turned around the Dual NPN, dead. Put new NPN, a programmed EEPROM from previous OEM and touched up some dull looking pins on the Interpreter and "Whal-la".

    It's up and running.

    Not sure what it was, but my GUESS was the pins on the Interpreter....will try and duplicate on next unit.

    will up date later
  • PublisonPublison Posts: 12,366
    hmlittle59 wrote: »
    Up-Date:
    Changed input communication Caps. 0.1uF NO change. Turned around the Dual NPN, dead. Put new NPN, a programmed EEPROM from previous OEM and touched up some dull looking pins on the Interpreter and "Whal-la".

    It's up and running.

    Not sure what it was, but my GUESS was the pins on the Interpreter....will try and duplicate on next unit.

    will up date later

    That's good news! Thanks for the update.


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