Add new images of v1.1. Update docs to reflect v1.1. Add notes about possible future versions.

README.md

@@ -4,26 +4,28 @@ https://github.com/xunker/bluescsi_pb
 
 This project allows you to use [BlueSCSI](https://github.com/erichelgeson/BlueSCSI) (STM32 SCSI emulator) in the Apple PowerBook, or in any other device that uses 40-pin 2.5in mobile SCSI devices.
 
-![Picture of bluescsi_pb connected to PowerBook 520c](images/headline.jpg)
+![Picture of bluescsi_pb connected to PowerBook 520c](images/headline_v1.1.jpg)
+
+# Compatibility
+
+Successfully used with my PowerBook 520c using the 40-pin connector. I have **not** yet been able to make it work with my PowerBook 145, however.
+
+Using the 50-pin connector, I have successfully used it with an Apple IIgs, a Macintosh Classic II and a Macintosh LC.
 
 # Board Versions and Gerber Files
 
 ## [version 1.1](v1.1/) (April 2021) - current
 
-v1.1 sent to fab today (Monday, Apr 5), hope to have to have it back by the weekend for testing.
-
-Changes:
-
+Changes in order of importance:
+* Mounting hole locations adjusted so they match an actual drive
 * Connect `RETURN` on 40-pin SCSI connector with signal ground
 * STM32 +5 is connected to `TERMPWR` by default, via breakable jumper pad
 * Separate jumpers provided for powering via `TERMPWR` or `MOTORPWR`
   - *MOTORPWR* is a separate +5v provided to run the drive motor and actuator
   - This change will be helpful for debugging power issues where *MOTORPWR* appears to be inconsistent
-* Mounting hole locations adjusted so they match an actual drive
 * Activity LED (`LED_BUILTIN`) broken-out if you want to have an external LED
-  - You can use the cathode (negative) pin of the LED footprint to monitor drive activity from an external device directly
-* Traces and resistor packs are moved farther away from mounting holes to avoid potential shorts
 * Increased `TERMPWR` trace width
+* Traces and resistor packs are moved farther away from mounting holes to avoid potential shorts
 * Back silkscreen marks location of the key pin (17) within the 40-pin connector
 * Moved legends for J1, J2 and J8 so they are next to pin 1 on their respective connectors
 * Corners rounded more
@@ -51,6 +53,38 @@ Why the modifications? the `MOTORPWR` pins do not appear to be working the way I
 
 ![3D rendering of bluescsi_pb v1.0 board ](images/pcb_v1.0_render.jpg)
 
+# Future Plans
+
+v1.1 is working well so I don't expect any majour changes for a while.
+## v1.2 (possible maintenance version)
+
+Plans for a v1.2 (maintenance) may include:
+
+* Jumper to toggle the activity LED
+  - So you can solder the LED and resistor, but disable it later if you prefer
+* Break out power LED
+  - Provide a power LED (and a jumper toggle) breakout if an external power LED is desired
+* Replace J4 & J5 with DIP switches or a single DPDT switch
+
+## v2.0 (possible full redesign)
+
+If I continue to develop project in the future, I plan on a full redesign.
+
+* Use termination ICs instead of resistors
+  - Lower power consumption
+  - More accurate termination voltage
+  - Switchable termination resistance (110-ohm or 2.5k-ohm) for short busses
+* Attach J1 & J2 via the PCB edge to make it more like how an actual hard drive connects
+* Less-expensive Micro SD card slot
+* Automatic switching between TERMPWR, MOTORPWR or USB Power
+
+If I want to fork the actual BlueSCSI firmware, I would like to add:
+
+* Separate LEDs for read and write activity
+* Read TERMPWR and MOTORPWR voltages and report them on the debugging connector
+* LEDs to indicate with SCSI ID is being accessed
+* Support OLED debugging display
+
 # Board Tour
 
 ## 40-pin connector (J1)
@@ -85,7 +119,42 @@ Pad J3 is used for a Molex 104031-0811 MicroSD card slot.
 
 If you do not have the correct part (or don't like soldering SMD, which is totally understandable), you can also solder 2.54mm male headers to an SD-to-MicroSD adapter and connect it to J7.
 
-![Picure of MicroSD connector pad and SD-to-MicroSD adapter with header pins soldered to it](images/low_rent_microsd_adapter.jpg)
+![Picture of MicroSD connector pad and SD-to-MicroSD adapter with header pins soldered to it](images/low_rent_microsd_adapter.jpg)
+
+## Power selection jumpers (v1.1+ only)
+
+By default the board is powered by SCSI termination power (`TERMPWR`), and is controlled by the joint JP1 (which is near J9).
+
+### Powering board by motor power (`MOTORPWR`)
+
+If you want to have the board be powered by +5 motor power (`MOTORPWR`) instead of `TERMPWR`, you must
+* Break joint **JP1** with a small knife
+* Solder a 2-pin header to **J10** and short it with a removable jumper cap
+
+This will power the Blue Pill module from `MOTORPWR`, but *SCSI termination* will still be powered by `TERMPWR`.
+
+### (Re)powering board by termination power (`MOTORPWR`)
+
+If JP1 is broken and you want reconnect the board back to `TERMPWR`, you must either:
+* Solder a 2-pin header to **J9** and short it with a removable jumper cap
+
+.. or ..
+
+* Resolder **JP1**
+
+### Powering board by USB alone
+
+If you want to power the Blue Pill module from USB power, you must:
+* Break joint **JP1** with a small knife
+* Ensure that **J9** AND **J10** are **NOT** shorted
+
+## Activity LED (D1) (v1.1+ only)
+
+![Picture of Disk Activity LED (D1)](images/activity_led.jpg)
+
+This is a breakout of the built-in LED that reflects disk activity. It is the same as the LED on the Blue Pill module itself. This part is **optional** and the module will work without it.
+
+The signal is active-low, and current-limiting resistor for the LED is on the *positive* (anode) side of the LED. This way you can tap in to the cathode (negative) pin of the LED footprint to monitor drive activity from an external device directly if you need to do that.
 
 # Caveats
 
@@ -97,6 +166,14 @@ Although documentation for the [IBM DHAS-2270](https://stason.org/TULARC/pc/hard
 
 .. I have found that this adapter does not want to work as the internal drive unless you enable termination. The PB 520c *does* supply termination power to the internal drive (although it *does not* supply it to the external HDI-30 SCSI connector).
 
+## 40-pin ribbon should not be seated fully on connector J1 (for me, at least)
+
+On my PowerBook 520c, seating the drive cable fully on to connector J1 causes the BlueSCSI module to not work. I have found that leaving the ribbon cable *slightly* (like, 1mm maybe) off the connector makes the connection much more reliable. See picture below so see how much I am talking about:
+
+![Picture of the 1mm gap between the ribbon cable and connector J1](images/j1_ribbon_recommended_gap_thumb.jpg)
+
+[Click here](images/j1_ribbon_recommended_gap_thumb.jpg) for larger version of above.
+
 ## Clearance
 
 Most SCSI PowerBooks used 17mm-tall SCSI drives. In order for this board to fit in that height, you will either need to permanently solder the STM32 module directly to the bluescsi_pb board or to use ["low-profile" female headers](https://www.adafruit.com/product/3008). If you use standard-height headers, you will need a space of 19-20mm.