Curious why Moteinos don't have SS Pullups Built In

Started by brandock, April 24, 2023, 01:37:29 PM

brandock

Recently I accidentally loaded firmware without a bootloader into a Moteino. I used ISP to recover it. While doing so I learned about using a pullup on SS to prevent the radio from interfering with ISP.

For example:
Quote from: TomWS on October 16, 2018, 10:37:27 AM
Also, if you do have a radio and flash memory, then you should have pullup resistors on pins 8 (Flash SS) & 10 (Radio SS) when programming via ISP interface.

My question: why not have these resistors on the Moteino as part of the board?

I've been designing a PCB with an onboard RFM transceiver and an ISP header. I am using pin 10 for Radio SS. In my design I have a Radio SS pullup resistor on the board that can be enabled with a jumper, to enable ISP. I could just as well leave it connected at all times, correct? Seems to work fine in my breadkboard tests.

But then I am wondering - why wouldn't Moteinos have any such pullup onboard? Little expectation of needed to use ISP? Space considerations? Just curious as I think about my PCB design. Thanks.

Felix

Because a lot of Moteinos are used without SPI/radio module.
Yes, if you know you will have the SPI always, then the pullup won't hurt to have.
Although the programming jig can have that. In real use the pullup is not needed. So it feels a bit redundant once you get past ISP programming.