Odd behavior from BS2 OEM boards
Otaku1031
Posts: 34
Hi all,
Been a while since I've posted here. I have 2 BS2 OEM boards that I'm using to operate relays via a pair of DS3658 lamp driver IC's. I'm getting some unusual behavior from my setup.
Here's the issue:
I'm using P13 and P14 on one BS2 board (BS2_A) as coded outputs to a second BS2 board (BS2_B). BS2_B receives the coded signals on P2 and P3 and, depending on the state of these inputs, it switches relays via a DS3658 IC. What is weird here is that when either of the two inputs is high, the BS2_B board is powering up. This happens even if I have no voltage on the Vdd pin of the BS2_B board. The two boards share a common power source (5VDC, 3.5A, regulated). I use LEDs to indicate when the boards are under power, and the LED for BS2_B lights when either P2 or P3 is high. If I then disconnect the ground to BS2_B, the LED goes out and the only voltage present is at P2 and/or P3, which comes from P13 and P14 on BS2_A.
This is the first time that I've tried using one BS2 to drive a second board. I assume that 5VDC input signals from one board shouldn't act to power up the second one, so perhaps I missed something in the configuration. Outside of the shared power source, the coded I/O is the only point of contact between the two boards.
Has anyone experienced this issue, and is there an explanation/solution? All help is appreciated!
Gary
Been a while since I've posted here. I have 2 BS2 OEM boards that I'm using to operate relays via a pair of DS3658 lamp driver IC's. I'm getting some unusual behavior from my setup.
Here's the issue:
I'm using P13 and P14 on one BS2 board (BS2_A) as coded outputs to a second BS2 board (BS2_B). BS2_B receives the coded signals on P2 and P3 and, depending on the state of these inputs, it switches relays via a DS3658 IC. What is weird here is that when either of the two inputs is high, the BS2_B board is powering up. This happens even if I have no voltage on the Vdd pin of the BS2_B board. The two boards share a common power source (5VDC, 3.5A, regulated). I use LEDs to indicate when the boards are under power, and the LED for BS2_B lights when either P2 or P3 is high. If I then disconnect the ground to BS2_B, the LED goes out and the only voltage present is at P2 and/or P3, which comes from P13 and P14 on BS2_A.
This is the first time that I've tried using one BS2 to drive a second board. I assume that 5VDC input signals from one board shouldn't act to power up the second one, so perhaps I missed something in the configuration. Outside of the shared power source, the coded I/O is the only point of contact between the two boards.
Has anyone experienced this issue, and is there an explanation/solution? All help is appreciated!
Gary
Comments
Do you have a schematic of your setup and how the power is wired? It isn't exactly clear to me from the description.
Are you saying that the first BS2 controls the power to the second module and that the second module is controlling relays? How are you powering on/off the second BS2? Do you have a common ground lead and switch on the main power to it or something else?
Thanks for the reply. I don't have a schematic at this time - the circuit is on a breadboard and is evolving as I get more feedback from the clinical group (we're a medical device company) as to the requirements. The first BS2 isn't controlling the power to the second one, it just sends I/O signals to P2 and P3 to trigger various subroutines depending on the coded input signals i.e. LOW-LOW, LOW-HIGH, HIGH-LOW and HIGH-HIGH. The second BS2 runs code loops that monitor P2 and P3 and trigger the appropriate routine based on the state of those pins.
The power is wired to both boards in parallel and is always on. Both boards control relays via the DS3658 IC's; the BS2's don't fire the relays directly from their outputs.
I just found what may be a significant problem. The radio frequency (460kHz) generator that is part of this system (the relays are used for switching the RF output to various treatment needles) is sending interference back up through the AC power line (110VAC). This interference was totally hashing the 5VDC rail voltage so I put the generator on a separate AC circuit and the interference disappeared. I'll be bringing the system back up within the hour to see if this makes a difference in the behavior. I'll post again when I have more info. Thanks again!
Gary