Victor, thanks for the comments. I think as long as you guys keep in mind that, while you're writing your libraries, that multiple devices should have unfettered access to the SPI buss, then you're ok. The Teensy ST7735 library code is really a mess in this regards. There are at least 3 major problems with the Teensy libraries, in regards SPI buss contention.
In any case - without getting too carried away --> It Works Now! I can talk to both ST7735 LCD and 23LC1024 SPI RAM chips now with the Teensy3.1 board.
You guys have been a big help. The past 2 days I've been looking at the Teensy SPI and ST7735 libraries, and trying to decipher the 50-page section on SPI in the d/s. As luck would have it, Ray posted about his o'scope project today, and I took a look at that. Turns out the ILI9341 LCD code for the STM32 is almost identical to the ST7735 LCD code for the Teensy, other than different register setups for the graphics chips, and except for the radical customizations the Teensy guy did.
So, using the STM32 ILI9341 SPI control code as a template, I rebuilt the Teensy ST7735 library, and the darn thing works the first time I try it. Foo. Now, I can put the OV7670 camera system all back together, and see how it goes. The LCD updates are a bit slower now, but I can work on that, now that the darn thing works at all, :-).
One thing I did discover, and possibly the STM32 chip registers are similar, is the Teensy code sends data to the SPI buss using the following command:
SPI0.PUSHR = c | (pcs_command << 16) | SPI_PUSHR_CTAS(0);
Here, c is the databyte, and variable pcs_command contains a mask to the CS bits to be automatically toggled, in this case both CS and DC. From the d/s:
21–16 PCS[5:0] Select which PCS signals are to be asserted for the transfer. Refer to the chip configuration chapter for the number of PCS signals used in this MCU.
0 Negate the PCS[.] signal.
1 Assert the PCS[.] signal.
So probably by changing this, plus some other setup stuff, I can manually toggle CS,DC and still use the more efficient SPI register operations. Maybe. In any case, another milestone marker passed, :-).
EDIT:
In any case, I'm following what you guys are doing with the LCD libraries, as I may be able to take advantage for my Teensy project. Thanks.