I2C to SPI bridge: SC18IS602 from NXP
Rayman
Posts: 14,876
This is a cool chip that I'm using in a couple projects, including PTP2.
I think it's a nice fit for the Prop and I don't think anybody has mentioned it here, so I thought
I'd just tell people about it, in case they didn't know...
As you know, the I2C eeprom uses P28 and P29. The Prop datasheet may imply that you can use
these pins as general purpose after boot up, but I don't think that's a good idea as there may
be some combination of states that cause the eeprom to short out of these pins, possibly damaging
anything attached.
So, I like to use I2C stuff on P28 and P29 as much as possible.
However, there are some things that only come in SPI...
This chip is great because you talk to it over I2C and it talks to your device with SPI.
You can actually control 4 SPI devices (if they share nicely).
If you don't need to control 4 spi devices, you can use the spared pins as general I/O.
Anyway, this is a great way to add SPI devices to your Prop without (from my point of view) using any otherwise free Prop pins.
I think it's a nice fit for the Prop and I don't think anybody has mentioned it here, so I thought
I'd just tell people about it, in case they didn't know...
As you know, the I2C eeprom uses P28 and P29. The Prop datasheet may imply that you can use
these pins as general purpose after boot up, but I don't think that's a good idea as there may
be some combination of states that cause the eeprom to short out of these pins, possibly damaging
anything attached.
So, I like to use I2C stuff on P28 and P29 as much as possible.
However, there are some things that only come in SPI...
This chip is great because you talk to it over I2C and it talks to your device with SPI.
You can actually control 4 SPI devices (if they share nicely).
If you don't need to control 4 spi devices, you can use the spared pins as general I/O.
Anyway, this is a great way to add SPI devices to your Prop without (from my point of view) using any otherwise free Prop pins.
Comments
A while ago I designed a series of "Qeeprom" or quasi-eeprom boards designed in 0.3" DIP8 format. I looked at the SC18IS60x but didn't realise they would actually fit the 5.08mm available, nor did I realise they were potentially good for 4 SPI. I think I went off them because the price is about the same as a small Freescale or Cypress micro that offers more flexibility, albeit with more complexity. Sometimes its just nice to have a peripheral chip that gets the job done
Here's a photo of your 3AD with the self stacking mill max connectors. You could do a similar thing with the SC18IS60x on one side of the PCB, 8 pin SPI device on the other, (just) within 0.3" limits
Let me know if you want any of these mill-max, I have many tubes from a surplus store here.
Nice pins.
I really do like those pins! That would let my mount a little gyro board on top of the 3AD for a 6DOF thingy...
I'll send some over for you to play with. They do come in different stack heights but all the ones I have are the size shown.
BTW I use a 1x9 female pin header with long pins for stacking. The total length is ~18.5mm and the female section is ~8.5mm or ~11mm. The ones I have are ~11mm but they can be made ~8.5mm by removing the 2.5mm spacer - its a little tedious. I also use 1x6 with total length ~23mm and the same female dimensions. PM me if you need any (pic on my stackable props thread)