[OpenTRV-dev] SMD version of ATmega328P

[Kevin Wood]

Yes, that would do it. It may not prove necessary but if the provision is
there on the board we're covered.

Kevin

> Hi,
>
> So I was thinking that maybe I put a weak pull-up on nSEL
?
>
> Rgds
>
> Damon
>
>
> On 24 Jul 2014, at 18:58, Kevin Wood <EMAIL ADDRESS HIDDEN> wrote:
>
>> Hi Damon,
>>
>> You're driving the MISO, MOSI, SCK and RESET lines to achieve in system
>> programming. As long as you don't exceed the voltage ratings of the
>> RFM23B's inputs (i.e. try to program the board at 5V) it shouldn't be
>> damaged, and as long as you don't assert the nSEL input to the RFM, it
>> won't be active, so will place a high impedance at those pins and
>> shouldn't corrupt the programming process.
>>
>> I don't see it presenting any problems but the proof of the pudding...
>>
>> I think the only thing that can scupper it is if the nSEL pin gets
>> asserted by the programming process. Will have to wade through the data
>> sheet to see if there are any guarantees there, but it would be sensible
>> if all the pins floated high during the ISP process.
>>
>> Kevin
>>
>> On 24/07/14 17:31, Damon Hart-Davis wrote:
>>> Hi,
>>>
>>> We’re starting production engineering work in earnest very soon, and
>>> we’re going to need to support in-circuit programming to use SMD.
>>>
>>> I believe the standard way to do this involves driving the SPI bus as
>>> for loading a bootloader.
>>>
>>> I am concerned that this cannot be done without damaging the RFM23B
>>> attached to the SPI bus, or am I wrong about that?  What gotchas don’t
>>> I even know about yet?
>>>
>>> Thanks
>>>
>>> Damon
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