Help with a Stamp2 Family Socket-based Prop form.
AwesomeCronk
Posts: 1,055
in Propeller 1
I am drafting in KiCAD ANOTHER project(I need to finish some of them one of these days.), which is a Propeller 1 form factor designed to snap into a BASIC Stamp 2 family socket. My questions are:
Which regulator should I use to bring Vin down to 3.3v?
How should I make a transistor-based(or resistor based) voltage shifter for the I/O?
Can I use the programming pins in the stamp socket for programming the prop?
Is this just absolutely preposterous?
Which regulator should I use to bring Vin down to 3.3v?
How should I make a transistor-based(or resistor based) voltage shifter for the I/O?
Can I use the programming pins in the stamp socket for programming the prop?
Is this just absolutely preposterous?
Comments
Package may determine it - do you want gull wing, or is DFN ok (new releases tend to be DFN ) ?
Do you want any voltage margin ? - many regulators are designed for 5.5V max, which helps keep the cost down, but are less tolerant than higher voltage units.
Do you want a Power Good (reset signal for Prop?)
If DFN is ok, I like the NCP187AMT330TAG for 5.5V/PG/1.2A and the LDFM33PVR is 16V/PG/500mA
Resistor shift is simple, but not very flexible and it is slow.
Better may be the chips designed for level shifting, with Auto-direction, which are often series N-FET in design. that acts as a low-Z up to 3v3, and then floats somewhat to be 5V tolerant.
A low on either side is rapidly transferred to the other side.
Examples :
http://www.ti.com/logic-circuit/voltage-level-translation/auto-bidirectional-voltage-translation/products.html
eg PCA9306, NVT20x series - pick a package you can handle and one that routes well. Some PCBs sprinkle more of smaller parts.
Look at the schematic for the Prop-mini for power and programming. I don't know how you'd fit the voltage translators for 16 I/O pins in the package you're thinking about. Resistors will only work for inputs
Shifter: I will follow that link and research later.
Programming: I guess support(and everyone here) must think I’m crazy. My guess is that it all comes down to I/O voltage levels and what firmware is on the chip. I will see if I can find out more.
Mike, I have the whole backside for that stuff.
BOOT SEQUENCE ------------- PC: set 115200-8-N-1 DTR low wait at least 10ms DTR high wait 100ms (+-10% tolerance) send $F9 (%0100111111 timing calibration) LFSR: taps = $B2, initialy = "P" send bitwise LFSR[250] ($FF/$FE) send $F9[250+8] for bitwise responses ($FE/$FF) receive bitwise LFSR[250] + version[8] within 50ms if timeout or mismatch, done (hardware not found error) send encoded command long (up to 3 bits sent per serial byte): 0 = shutdown 1 = load ram, then run 2 = load ram+eeprom+verify, then shutdown 3 = load ram+eeprom+verify, then run if command 0, done (okay) send encoded length long send encoded data longs send $F9 every 10ms for bitwise response(s): if command 1-3, receive bitwise checksum pass/fail within 10(?) seconds if timeout, done (connection error) if checksum fail, done (checksum error) if command 1, done (okay) if command 2-3, receive bitwise program pass/fail within 5 seconds if timeout, done (connection error) if program fail, done (program error) receive bitwise verify pass/fail within 2 seconds if timeout, done (connection error) if verify fail, done (verify error) done (okay) CHIP: <reset> wait for up to 150ms @20MHz for $F9 + bitwise LFSR[250] if timeout or mismatch, EEBOOT use incoming $F9 bytes to convey bitwise LFSR[250] + version[8] receive encoded command[32]: if command 0, 4+: SHUTDOWN if command 1..3: receive encoded length[32] receive encoded data[32], dump into $0000..length<<2-1 fill length<<2..$7FFC with $00 write dbase @$0008 structure: long[dbase-4] = $FFF9FFFF, long[dbase-8] = $FFF9FFFF bytewise sum $0000..$7FFF for checksum verify if checksum failure, convey error on next $F9, SHUTDOWN else, convey okay on next $F9 if command 1, LAUNCH if command 2-3: program eeprom from ram if eeprom timeout (10ms @20MHz), convey error on 2nd $F9, SHUTDOWN else, convey okay on next $F9 verify eeprom against ram if verify fail, convey error on 2nd $F9, program $0004 to $00 in eeprom, SHUTDOWN else, convey okay on next $F9 if command 2, SHUTDOWN if command 3, LAUNCH EEBOOT: read eeprom into ram LAUNCH LAUNCH: if word at $0004 is not $0010, SHUTDOWN setclk(byte[15] & $78) wait 50ms at 20MHz setclk(byte[15]) launch interpreter from $0004 in current cog SHUTDOWN: dira=0, setclk($01)The voltage translation is based on an application note from Philips for use with I2C. Again, there's lots of information on this on Adafruit's and SparkFun's websites. A number of level shifters are for 4-bits, so you'd need 4 of them. The programming is done at 3.3V, so you won't need level shifting for ATN, Sin, or Sout. You will need to use a PropPlug or equivalent instead of the Stamp's USB to serial adapter for programming. If you want the devices to be strictly Stamp hardware equivalents, you'll need another voltage translator for Sin and Sout. You may need a couple of capacitors and resistors for ATN. You also may need a package of 3.3V inverters. The Prop's programming protocol is not at all similar to that of the Stamps and is in masked ROM.The Propeller could be programmed to behave like a Stamp. It would start up in a Stamp loader and load Stamp interpretive code into part of the 64K Propeller EEPROM. You'd need to write a Stamp interpretive code interpreter. Unfortunately, I'm not aware of any public documentation on the interpretive code. Maybe you could convince Ken or Chip to make it available for this project.
As anything aside from the experience, this would be a bust.
https://www.ebay.com/itm/US-Stock-10pcs-2-54mm-Male-40-Pin-Single-Row-Round-Header-Strip-Gold-Plated-New/401261238204
They're called round-pin header strips, and the pin diameter is much less than the 0.025" square pins you're familiar with.
In my experience, the edge-soldered flat-pin connectors are almost impossible to source.
-Phil
We used to use a sacrificial DIP socket, to transition from square pins to DIP image.
The square pins can be persuaded to go into a Dual wipe DIP socket, but do deform it, so a dedicated 'bridge' socket protects the host socket(s) and is very low cost and easy to find
Where you have top-bottom conflicts, we used to apply 'special treatment' to the inner pins on adapters, using standard square pin headers, sometimes with longer pins.
The std header was made a snug (almost press fit) into the outer thru holes, and the inner few pins that needed to be one-sided were either bent to gull-wing them, or in very tight cases just clipped flush with PCB plane, and then soldered onto a oval pad.
https://forums.parallax.com/discussion/143318/35-mini-propeller-module-propbsc-cancelled/p1
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