[TangerineSDR] TangerineSDR Digest, Vol 31, Issue 1

Julius Madey hillfox at fairpoint.net
Tue Oct 5 22:28:09 EDT 2021


Bill,
Still not sure what the confusion is.  Definitely the JMP4 call out in 
the table is incorrect; it should be JMP1. JMP4 is only used to connect 
the CAT cable shield to the board ground.

However, the JMP1 /position/ can have a maximum of three jumpers 
installed ... in which case, all three bits are 0's.
So the condition shown in the list above table2 for the 9808 address 
0x18 is correct: either all three JMP1 positions installed in a remote 
board or plugged on as a PiHAT, JMP1 positions 3-4 and 5-6 occupied with 
position 1-2 'occupied' by the grounding of A0 at the Pi header.

If you want to use address 0x1E, either occupy position 1-2, leaving the 
others open OR use the board as a PiHAT, leaving the other positions open.

Scotty set the board up for the possibility of directly installing the 
PNI MAG ASIC plus three orthogonal sensing inductors and accompanying 
bias resistors along with a couple of other components on the PC board, 
without using the PNI RM3100 test board product as a plug in.

However, JMP2 doesn't appear in the schematic and it's stated function 
to disable RM3100 i2c addressing was probably intended to disable an 
RM3100 test board if it was plugged into the female header on the board 
in addition to the direct installation on the board of the equivalent 
components. However, other than not supplying 3.3 volt power to an 
RM3100 plug in, there is no simple way of completely disabling it .... 
other than not plugging it in !  Not sure why we didn't catch that in 
the proofread.

One other thing:  the note on the schematic by the 9808 stating:

LOCAL/STND ADR:0x1E
REMOTE ADR: 0x1F

should read:
LOCAL/STND SDR: 0x18
REMOTE ADR: 0x19

To comply with what Dave Witten has been working with in control 
software so far.

Regards,
Jules-K2KGJ




On 10/5/2021 7:59 PM, Bill Owens wrote:
> I marked up the PDF to try to explain what I was seeing - hopefully it 
> will make more sense now. I realized another oddity exists in the 
> description as well; JMP2 is called out but does not seem to exist in 
> the current schematic. I'm guessing the description page was written 
> for an earlier rev that had a more limited set of address selections, 
> and had JMP2 in the circuit.
>
> Bill.
>
> On Sun, Oct 3, 2021 at 3:47 PM Julius Madey <hillfox at fairpoint.net 
> <mailto:hillfox at fairpoint.net>> wrote:
>
>     Bill,
>     This is the i2c address space of the 9808 and RM3100 per the data
>     sheets......0 is ground and 1 is Vdd
>
>
>
>
>     I think you meant that JMP4 in the second column should be JMP1
>     rather than the other way round.  JMP4 is the shield ground.
>
>     When the local board is plugged on the Pi 40 pin header as a
>     PiHAT, A0 is pulled low, which limits the possible address space
>     for the RM3100 on the local board to 0x20 and 0x22, and the local
>     9808 to 0x18, 0x1A, 0x1C and 0x1E.
>
>     For the remote board, all addresses in the above table are
>     available......except that used for the 9808 on the local board. 
>     If no address jumpers are installed on the local board, then 9808
>     addresses 0x19 through 0x1F are available at the remote.
>
>     Note that no more than four RM3100s can be used on the same i2c
>     bus ... expansion beyond that requires an i2c multiplexer like the
>     TCA9548a which Dave Witten and I were considering for a test board
>     for the RM3100 that would service some 32 RM3100s.
>
>     CAUTION regarding the note under extended mode in the address
>     tables and the use of multiple 9615 differential i2c drops on the
>     CAT5 or CAT6 cable.  Read the 9615 data sheet carefully on the
>     subject of multiple drops .... intended for short (~ 3meter cable
>     runs) at a 1MHz bus speed.  My testing to 400+ feet was with only
>     a local and remote board at 100KHz bus speed which demonstrated
>     well behaved transmission line behavior for the ~100ohm twisted
>     pair lines in the cable with no reflections and no transient spikes.
>
>     The 9615 data sheet example for multiple drops on the differential
>     lines show NO termination resistances on the intermediate drops
>     and only line terminations at the beginning and end 9615s.   I'm
>     going to hazard a guess that you might be able to use 100 feet or
>     so of cable with a couple of intermediate drops within 3 or 4 feet
>     of the remote end and NO terminations on the 9615s on those boards
>     but would have to actually scope test that to verify.
>
>     The only multiple mag install on a single CAT cable I am aware of
>     is the one I'm using here with two RM3100 remote boards within
>     about 3 inches of one another connected only by ground, +3.3V, SDA
>     and SCL  (eg i2c bus connections only).
>
>     Regards,
>     Jules-K2KGJ
>
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>     On 10/2/2021 11:36 PM, Bill Owens wrote:
>>     I did get the email - thank you! I looked through the info on the
>>     second page of the PDF and I have some questions, but it does
>>     confirm that there are options for as many as four sensor boards,
>>     which fits with what I was considering.
>>
>>     I think the box below the I2C table is wrong for the MCP9808; the
>>     addresses should be 0x1E and 0x1F per the table, and the callout
>>     in the schematic. It also mentions JMP1 in the second column, I
>>     think that should be JMP4.
>>
>>     I also noted that JMP4 is described as being set only on the
>>     local board in most locations, but shown as "Placed" on the
>>     remote board in the NORMAL MODE and EXTENDED MODE boxes.
>>
>>     I'm curious about whether there's a plan for deploying multiple
>>     sensors; one of the notes implies that, without giving any other
>>     details. Would it be a star configuration with the Pi at the
>>     center, or a daisy-chain using both the RJ45 and J10 for the
>>     boards in the middle?
>>
>>     Thanks,
>>     Bill N2RKL
>>
>>     On Sat, Oct 2, 2021 at 1:54 PM Julius Madey via TangerineSDR
>>     <tangerinesdr at lists.tapr.org
>>     <mailto:tangerinesdr at lists.tapr.org>> wrote:
>>
>>         I answered Bill a few days ago....perhaps he didn't receive
>>         the email.   I forwarded the latest schematic and layout for
>>         the board which has a section on setting i2c addresses. 
>>         Perhaps Scotty can update that further.
>>         Jules-K2KGJ
>>
>>
>>         On 10/2/2021 12:00 PM, tangerinesdr-request at lists.tapr.org
>>         <mailto:tangerinesdr-request at lists.tapr.org> wrote:
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>>>         Today's Topics:
>>>
>>>             1. FW: [HamSCI] Two questions about the new TAPR magnetometer
>>>                board (Dr. Nathaniel A. Frissell Ph.D.)
>>>
>>>
>>>         ----------------------------------------------------------------------
>>>
>>>         Message: 1
>>>         Date: Fri, 1 Oct 2021 16:22:25 +0000
>>>         From: "Dr. Nathaniel A. Frissell Ph.D."
>>>         	<nathaniel.frissell at scranton.edu>  <mailto:nathaniel.frissell at scranton.edu>
>>>         To:"tangerinesdr at lists.tapr.org"  <mailto:tangerinesdr at lists.tapr.org>  <tangerinesdr at lists.tapr.org>  <mailto:tangerinesdr at lists.tapr.org>
>>>         Subject: [TangerineSDR] FW: [HamSCI] Two questions about the new TAPR
>>>         	magnetometer board
>>>         Message-ID:
>>>         	<BLAPR03MB5540044997C2145BB6D46D2AF2AB9 at BLAPR03MB5540.namprd03.prod.outlook.com>  <mailto:BLAPR03MB5540044997C2145BB6D46D2AF2AB9 at BLAPR03MB5540.namprd03.prod.outlook.com>
>>>         	
>>>         Content-Type: text/plain; charset="us-ascii"
>>>
>>>         Hi,
>>>
>>>         I'm sending these questions from Bill N2RKL to the TangerineSDR list. They were originally posted on the HamSCI list.
>>>
>>>         73 Nathaniel
>>>
>>>         From:hamsci at googlegroups.com  <mailto:hamsci at googlegroups.com>  <hamsci at googlegroups.com>  <mailto:hamsci at googlegroups.com>  On Behalf Of Bill Owens
>>>         Sent: Thursday, September 30, 2021 9:22 AM
>>>         To: HamSCI<hamsci at googlegroups.com>  <mailto:hamsci at googlegroups.com>
>>>         Subject: [HamSCI] Two questions about the new TAPR magnetometer board
>>>
>>>         I've listened to the last couple Zoom sessions and also found the layout pictures that Scotty showed a few weeks ago, but I haven't been able to work out answers for two questions:
>>>
>>>           - How many I2C addresses can be set for the magnetometer and the temperature sensor on each board?
>>>           - Are the RM3100 components soldered on the boards, or perhaps on half of them? It looks like there are options for SMT header sockets, and for the components themselves.
>>>
>>>         Thanks,
>>>         Bill N2RKL
>>>         --
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>>>         End of TangerineSDR Digest, Vol 31, Issue 1
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>>
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