I got the NVSRAM chips in on Monday. In layman's terms these new chips are equivalent to flash memory - their contents can be changed on the fly. In this case the ECU itself is going to do the changing. I had to write a program within the ECU to change the contents of the NVSRAM over the serial port, but in order to even get that to work, you have to put the initial program on the chip.
You might ask why go through all of this trouble when the moates ostrich already handles emulation. Well there are two reasons, first off is cost - the ostrich retails around $200 while the NVSRAMs can be sourced under $50.00. The second and primary reason is that the programming is done over the ecu's serial port - this enables a single serial connection to control emulation and datalogging. This serial connection can be via USB or bluetooth.
Unfortunately my EPROM programmer doesn't handle the new chips, but thankfully I am the master of using things inappropriately.. Since I have complete control of the ECU and it's microprocessor and coding, why not use the ECU to program the NVSRAM? I installed a riser board with two sockets, extended the address and data bus to the second socket and installed some basic logic to handle the chip enable, read and write signals. There is also a switch that controls the mode of the processor. When it's flipped up it's in programming mode - it switches the internal ROM off and the processor's 0 page is rerouted to the left chip (source). The source can be either an eprom chip or the Ostrich. The source chip contains a simple program to boot the processor and copy the contents of the program stored within itself to the NVSRAM (destination).
When the switch is flipped down, the ECU resumes normal operation with the NVSRAM activated as the primary chip, allowing me to test the chip I just programmed! I could leave everything as-is with the riser card and install it in the car and test the chip. The jumper on the circuit board controls which half of the NVSRAM gets the program - left position programs the automatic side, right position programs the manual side. It doesn't matter if the source chip is installed or not still because it's chip enable signals are no longer valid with the processor in normal mode. (this was one of those convenient accidental discoveries lol)
Thankfully, once the chip is programmed it can be installed directly into ecu without any riser card. A few simple (reversible) hardware changes have to be done to enable the write signal to the chip and account for a relocated address line. The final product will look something like this:
Note that in the picture above there is an extra socket sandwiched between the NSVRAM and the board. The final product will include a low profile socket and much neater wiring. Thankfully it just BARELY clears the A/T daughterboard with the low profile socket.
My "lab" 5/5/12
-Matt
