Empathy List Archives

You don’t say how you are connecting to the Rb. The manual states:

 You have too many 1s in your startup string compared to the expected "PRS_10\r".
 If the MCU clock is not 10Mhz then the integrated UART rates will be off,
 which should produce framing errors, but do UARTs still detect and systems
 report these nowadays, or just pass along garbled data?
 Otherwise, garbled data is most often a result of inadequate pin contact,
 if the connectors are not seated properly, or the pins or sockets are loose
 in their shells.
 Age and rough treatment can have that effect.

 "Internal hardware jumpers allow these pins to be configured as analog outputs
 to monitor the lamp intensity and varactor voltage for complete compatibility
 with the FRS."
 Have you checked the jumpers in the manual Configuration Notes:
 "Pin 4: TXD/PHOTO The default configuration uses this pin as an output for RS-232 data.
 Many system parameters (including the lamp intensity) may be monitored via the RS-232
 interface. The function of this pin may be changed to an analog monitor for the lamp
 intensity by removing one resistor (R347) and installing a 10 kΩ resistor for another (R348)
 on the microcontroller PCB."

 On 2015-08-24 22:40, Brian M wrote:
     I tried through the weekend, double and triple checking wiring and setup.
     I've tried the following methods of getting serial comms working:
     PRS10 -> Arduino Uno (with processor bypassed) -> USB Host
     PRS10 -> Level Shifter -> BBB UART
     PRS10 -> MAX232 -> USB Serial adapter

     Shortly after power is applied to the PRS10, I do get a string of
     characters. Believe it should be the model information. Instead I get:
     wy+VPgy

     I guess the good news is that this output appears consistent with each
     power cycle of the device. And I'm getting the same results through all the
     hookup methods I've tried.

     My minicom settings are for software flow control at 9600 8N1 - from what
     the manual states, this should be the right settings. I've tried screen as
     well - and get the same text. I went crazy trying several other rates and
     setting combinations. No luck.

     Maybe I've missed something obvious.

     I agree that getting comms going to the MCU are going to be an important
     step. How do people address this type of problem? Scope the serial and try
     to decode by hand? The 10Mhz to the MCU looks OK on a scope. Are there
     further steps people try after that? If nothing else I think there's some
     interesting stuff to learn here. I also wouldn't mind tearing out the
     electronics, determining if the lamp is good, and attempt to build from
     there. I don't know the datecode for the unit, the PCB is marked with a
     datecode suggesting 2003? I don't have the full case. I'm trying to assess
     what are reasonable next steps. How do I determine if the MCU is healthy?
     If the MCU is fried, how do I determine if I just need to squeeze a new MCU
     board in there?

     Thanks! I appreciate the input so far!
     - Brian

     PS - after looking again at the signal on the scope, it does seem like it
     is 9600 baud. ~100µS per bit. The data out on the MCU itself looks like
     what I saw on the main connector.

     On Sat, Aug 22, 2015 at 2:04 PM Mike Cook <michael.cook@sfr.fr> wrote:

             Le 22 août 2015 à 03:40, Bob Camp <kb8tq@n1k.org> a écrit :

             Hi

             On any microprocessor based gizmo, getting the micro running (again) is
             generally priority number one. It sets everything up and gives you the

         diagnostic

             info you need to go further. Garbled serial is better than none at all.

         It suggests

             something short of a total MCU death spiral …

             Bob

                 On Aug 21, 2015, at 7:26 PM, Brian M <brayniac@gmail.com> wrote:

                 Dear list -

                 I have come into possession of a for parts prs 10. I'd like to try to
                 repair this device. What I've noticed so far. Serial is garbled. (Even

         at

                 varying baud rates).

            You don’t say how you are connecting to the Rb. The manual states:
         "RS-232 data is sent to the host on pin 4, received from the host on pin
         7. The baud rate is
         fixed at 9600 baud, 8 bits, no parity, with 1 start and 1 stop bit. No DTR
         or CTS controls are
         used; rather, the XON/XOFF protocol has been implemented. The transmit
         drive level is 0
         and 5 V, not the +/-12 V normally associated with RS-232. These levels are
         compatible with
         most RS-232 line receivers, but does not require their use (a TTL inverter
         may be used
         instead), hence simplifies the interface when used inside an instrument at
         the sacrifice of
         degraded noise immunity over long lines."

         So make sure that you adhere to that.

                 Lamp isn't lit.

         What’s the date code. Early versions may be reaching EOL, though 20yrs id
         quoted.

                 Doesn't look great. I'd like to know
                 if anybody else has wandered down this path. What are common failure

         modes?

                 Anything match up with what I describe? Voltages to check would be

         helpful.

                 The 10MHz out looked okay on a scope. Haven't gone further yet. I

         suspect

                 the crystal is fine.

                 Thanks in advance. Happy hacking!

time-nuts@lists.febo.com

SRS PRS10 repair