JM002 Expansion Serial IO Mezzanine Board [v2.0] for SC126 V1.0

Version 2.0: Updated to use functional uSD card adpaters that respect the CS signal - not hard tied active. Most of the 6-pin adapters do not respect proper sensing of the chip select - instead, the module ties CS active ALL THE TIME. These modules prevent having more than one slave on the SPI circuit. There is a solution: Adafruit has an 8 pin uSD card module that works correctly where SPI modules can be attached to the two (2) SPI ports on the SC126 V1.0 card. The adafruit item is: Item #254, Mouser Part: 485-254. Adafruit Description: "MicroSD card breakout board+." P14 and P7 have been modified to include the required 6 lines from teh SC126 headers on the JM002 card. The layout has changed for P14 and P7 to enable the card adapters to extend out from the board for my "SC126 Stacked V2.0" 3D printed enclosure. You may need to modify the location of these plugs to suit your final enclosure. Version 1.2 is created to fix DE-9 pin 2 adn pin 3 reversal - not standard and requires null modem equivalant cabling when it shouldn't to most attached devices. Now straight through cable will work when attached to printer, etc. Version 1.1 is created after prototype testing. Added CTC for broad range baud rate control. Create a stackable daughterboard for SC126 - intent, change packaging of the IO interfaces to a denser and flatter format (flat instead of Manhattan style) and add additional features (SIO/0 or /2 - selectable) to the daughterboard. Board will lay on top of the SC126; the Daughterboard S3 connector mates with the SC126 S3 connector. Several of the SC126 headers mate with the Daughterboard so that the SD and TTL-USB modules can lay flat when populated with straight instead of angled pin headers. Direct solder is also an option. The stack-up has been finalized. Cutaways are provided for access to the RTC Clock Battery on the SC126 as well as for LED wiring clearance OK for USE - evaluated with RomWBW 3.1pre5 and it is configurable via MODE.COM and build configuration parameters V1.1 corrected silk screen and added 10K pull up jumpers for IM 2 IE and IEO