Macintosh-SW
/
mac-rom-simm-programmer
mirror of https://github.com/dougg3/mac-rom-simm-programmer.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Add pulldown (5V short detection) to SIMM electrical test

This commit is contained in:
Doug Brown 2023-08-06 20:35:30 -07:00 committed by Doug Brown
parent c6313d0859
commit 96b5b2034b
1 changed files with 111 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

112
tests/simm_electrical_test.c
View File

@ -24,6 +24,7 @@
#include "simm_electrical_test.h"
#include "../hal/parallel_bus.h"
#include "hardware.h"
#include "board_hw.h"
/// The index of the highest SIMM address pin
#define SIMM_HIGHEST_ADDRESS_LINE 20
@ -40,6 +41,8 @@
/// The index reported as a short when it's a ground short
#define GROUND_FAIL_INDEX 0xFF
/// The index reported as a short when it's a +5V short
#define VCC_FAIL_INDEX 0xFE
/// The index reported when A0 is shorted
#define FIRST_ADDRESS_LINE_FAIL_INDEX 0
/// The index reported when A20 is shorted
@ -101,10 +104,15 @@ int SIMMElectricalTest_Run(void (*errorHandler)(uint8_t, uint8_t))
ParallelBus_SetOEDir(false);
ParallelBus_SetWEDir(false);
ParallelBus_SetAddressPullups(SIMM_ADDRESS_PINS_MASK);
ParallelBus_SetAddressPulldowns(0);
ParallelBus_SetDataPullups(SIMM_DATA_PINS_MASK);
ParallelBus_SetDataPulldowns(0);
ParallelBus_SetCSPullup(true);
ParallelBus_SetCSPulldown(false);
ParallelBus_SetOEPullup(true);
ParallelBus_SetOEPulldown(false);
ParallelBus_SetWEPullup(true);
ParallelBus_SetWEPulldown(false);
// Wait a brief moment...
DelayMS(DELAY_SETTLE_TIME_MS);
@ -196,7 +204,109 @@ int SIMMElectricalTest_Run(void (*errorHandler)(uint8_t, uint8_t))
// OK, now we know which lines are shorted to ground. We need to keep that
// in mind, because those lines will now show as shorted to ALL other
// lines...ignore them during tests to find other independent shorts
// lines...ignore them during tests to find other independent shorts.
// If the arch also supports checking for shorts to VCC, check for those next.
#if BOARD_SUPPORTS_PULLDOWNS
ParallelBus_SetAddressPullups(0);
ParallelBus_SetAddressPulldowns(SIMM_ADDRESS_PINS_MASK);
ParallelBus_SetDataPullups(0);
ParallelBus_SetDataPulldowns(SIMM_DATA_PINS_MASK);
ParallelBus_SetCSPullup(false);
ParallelBus_SetCSPulldown(true);
ParallelBus_SetOEPullup(false);
ParallelBus_SetOEPulldown(true);
ParallelBus_SetWEPullup(false);
ParallelBus_SetWEPulldown(true);
// Wait a brief moment...
DelayMS(DELAY_SETTLE_TIME_MS);
// Now loop through every pin and check it.
curPin = 0;
// Read the address pins back first
readback = ParallelBus_ReadAddress();
// Check each bit for a HIGH which would indicate a short to VCC
for (i = 0; i <= SIMM_HIGHEST_ADDRESS_LINE; i++)
{
// Did we find a high bit?
if (readback & 1)
{
// That means this pin is shorted to VCC.
// So notify the caller that we have a VCC short on this pin
if (errorHandler)
{
errorHandler(curPin, VCC_FAIL_INDEX);
}
// And of course increment the error counter.
numErrors++;
}
// No matter what, though, move on to the next bit and pin.
readback >>= 1;
curPin++;
}
// Repeat the exact same process for the data pins
readback = ParallelBus_ReadData();
for (i = 0; i <= SIMM_HIGHEST_DATA_LINE; i++)
{
if (readback & 1)
{
if (errorHandler)
{
errorHandler(curPin, VCC_FAIL_INDEX);
}
numErrors++;
}
readback >>= 1;
curPin++;
}
// Check chip select in the same way...
if (ParallelBus_ReadCS())
{
if (errorHandler)
{
errorHandler(curPin, VCC_FAIL_INDEX);
}
numErrors++;
}
curPin++;
// Output enable...
if (ParallelBus_ReadOE())
{
if (errorHandler)
{
errorHandler(curPin, VCC_FAIL_INDEX);
}
numErrors++;
}
curPin++;
// Write enable...
if (ParallelBus_ReadWE())
{
if (errorHandler)
{
errorHandler(curPin, VCC_FAIL_INDEX);
}
numErrors++;
}
curPin++; // Doesn't need to be here, but for consistency I'm leaving it.
// Clear the pulldowns now that we're done; we won't need them anymore
// for the rest of the testing
ParallelBus_SetAddressPulldowns(0);
ParallelBus_SetDataPulldowns(0);
ParallelBus_SetCSPulldown(false);
ParallelBus_SetOEPulldown(false);
ParallelBus_SetWEPulldown(false);
#endif
// Now, check each individual line vs. all other lines on the SIMM for any
// shorts between them