Configuring the external memory settings is a bit tricky, so here is a detailed explanation of what each setting does and known-good values for particular hardware configurations.
Note that these are specific to MegaYume. Note that MegaYume uses slightly different clock speeds depending on video mode, so a timing that just barely works in one mode might not in another.
Since this is the most common config, these are the default values in config.spin2.
' Enable one of these to select the exmem type to use
#define USE_PSRAM16
'#define USE_PSRAM8
'#define USE_PSRAM4
'#define USE_HYPER
PSRAM_CLK = 56
PSRAM_SELECT = 57
PSRAM_BASE = 40
PSRAM_BANKS = 1 ' Only used to stop further banks from interfering
PSRAM_WAIT = 5
PSRAM_DELAY = 13
PSRAM_SYNC_CLOCK = false
PSRAM_SYNC_DATA = false
' Uncomment for slower memory clock
'#define USE_PSRAM_SLOW' Enable one of these to select the exmem type to use
'#define USE_PSRAM16
#define USE_PSRAM8
'#define USE_PSRAM4
'#define USE_HYPER
' For PSRAM (either type)
PSRAM_CLK = 8 addpins 1
PSRAM_SELECT = 10
PSRAM_BASE = 0
PSRAM_BANKS = 6 ' Only used to stop further banks from interfering
PSRAM_WAIT = 5
PSRAM_DELAY = 17
PSRAM_SYNC_CLOCK = true
PSRAM_SYNC_DATA = true
' Uncomment for slower memory clock
#define USE_PSRAM_SLOW' Enable one of these to select the exmem type to use
'#define USE_PSRAM16
'#define USE_PSRAM8
#define USE_PSRAM4
'#define USE_HYPER
' For PSRAM (either type)
PSRAM_CLK = 48+4
PSRAM_SELECT = 48+5
PSRAM_BASE = 48
PSRAM_BANKS = 3 ' Only used to stop further banks from interfering
PSRAM_WAIT = 5
PSRAM_DELAY = 15
PSRAM_SYNC_CLOCK = true
PSRAM_SYNC_DATA = true
' Uncomment for slower memory clock
'#define USE_PSRAM_SLOW' Enable one of these to select the exmem type to use
'#define USE_PSRAM16
'#define USE_PSRAM8
'#define USE_PSRAM4
#define USE_HYPER
' For HyperRAM
HYPER_ACCESSORY = 0 ' Base pin for P2EVAL HyperRAM board
HYPER_CLK = 8+HYPER_ACCESSORY
HYPER_RWDS = 10+HYPER_ACCESSORY
HYPER_SELECT = 12+HYPER_ACCESSORY
HYPER_BASE = 0+HYPER_ACCESSORY
HYPER_RESET = 15+HYPER_ACCESSORY
HYPER_LATENCY = 6
HYPER_WAIT = HYPER_LATENCY*4 - 2
HYPER_DELAY = 13
HYPER_SYNC_CLOCK = false
HYPER_SYNC_DATA = falseOne of these defines must be enabled to select the RAM type and bus width used (and thus the number of RAM chips in parallel).
USE_PSRAM4 -> single PSRAM chip
USE_PSRAM8 -> dual PSRAM chips
USE_PSRAM16 -> quad PSRAM chips
USE_HYPER -> single HyperRAM chip
Note that HyperRAM uses separate constants to PSRAM, but they act the same.
PSRAM clock output pin. This can be any pin (and if needed, 3 additional clock pins may be added using addpins syntax).
PSRAM select pin. This can be any pin.
Number of PSRAM banks to use. The second bank will use PSRAM_SELECT + 1 as its select pin (and so on for the third, etc). Note that in any case, MegaYume only requires one bank, any additional ones will not be used, but this value must still be set correctly to avoid interference from the unused banks.
PSRAM data bus base pin. This must be a multiple of 8 (or 4 if USE_PSRAM4) and the data pins must be connected to this in order.
Number of data bit periods between address send and data return. Leave this value at 5 unless you have a different type of memory chip.
For HyperRAM, please set this indirectly through HYPER_LATENCY, which is the default latency setting as documented in your memory data sheet.
Read delay compensation in P2 machine cycles. Try changing this value if you have problems.
Enables P_SYNC_IO mode on the data bus. This is a sort-of "half step backwards" for PSRAM_DELAY and should be adjusted alongside it.
Enables P_SYNC_IO mode on the clock pin. This is a further timing adjustment. In most cases you can leave it on true.
Enables a slower bus speed (CPU clock divided by 3 instead of 2). This is useful for setups with a large number of banks. Not available for HyperRAM.