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Thought for 7 sec — Determining layout skills

Looking up How should thermal relief be applied to top-layer ....

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Reading layout details for U3, U1, SW2 and 15 more.

Reading layout details.

Reading more of the layout.

Editing layout rules.

Reading more of the layout.

Thought for 1 sec

flux

Set P1's thermalRelief to "Relief connect"
Set P1's thermalRelief to "Relief connect"
Set GND's thermalRelief to "Relief connect"
Set P1's thermalRelief to "Relief connect"
Set VSS's thermalRelief to "Relief connect"
Set K's thermalRelief to "Relief connect"
Set 1's thermalRelief to "Relief connect"
Set P1's thermalRelief to "Relief connect"
Set S's thermalRelief to "Relief connect"
Set P2's thermalRelief to "Relief connect"
Set PIN2's thermalRelief to "Relief connect"
Set SHIELD's thermalRelief to "Relief connect"
Set SHIELD's thermalRelief to "Relief connect"
Set SHIELD's thermalRelief to "Relief connect"
Set GND's thermalRelief to "Relief connect"
Set SHIELD's thermalRelief to "Relief connect"
Set SHIELD's thermalRelief to "Relief connect"
Set SHIELD's thermalRelief to "Relief connect"
Set P1's thermalRelief to "Relief connect"
Set P1's thermalRelief to "Relief connect"
Set 5's thermalRelief to "Relief connect"
Set 4's thermalRelief to "Relief connect"
Set S's thermalRelief to "Relief connect"
Set THR's thermalRelief to "Relief connect"
Set GND's thermalRelief to "Relief connect"
Set +'s thermalRelief to "Relief connect"

Thought for 3 sec

flux

Updated 26 top-layer pads connected to the GND net to use thermalRelief = Relief connect. Verified the updated GND pads now compute as thermalReliefType: Relief connect; component placement, routing, and net connectivity were not changed. DRC still reports existing dangling/floating/overlapping copper issues, but no new thermal-relief-specific issue was reported.

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Files

Schematic

Layout

3D View

J1

R4

Resistance

H3

R3

Resistance

R5

Resistance

R6

Resistance

R8

Resistance

H4

R10

Resistance

R7

Resistance

R2

Resistance

R9

Resistance

R11

Resistance

H1

R1

Resistance

H2

C2

Capacitance

.1

U1

C3

Capacitance

Q2

D1

C1

C4

Capacitance

Q1

D2

LED1

SW1

J2

SW2

BZ1

LED2

U3

Manufacturer Part Number

NE555D

U2

STM32F429IIT6 to AS4C4M16S-6TINTR SDRAM Wiring

Summary

Use the STM32F429IIT6 FMC SDRAM interface in 16-bit SDRAM mode. The AS4C4M16S is a 64 Mbit, 4M x 16 SDRAM with A0-A11, BA0-BA1, DQ0-DQ15, LDQM/UDQM, CLK, CKE, CS#, RAS#, CAS#, and WE#.

Recommended STM32 control-pin choice: use the PH2/PH3/PH5 FMC SDRAM control options for SDCKE0, SDNE0, and SDNWE to keep PC0/PC2/PC3 free unless you have a layout/peripheral reason to use the PC alternatives.

Core signal mapping

Table

SDRAM pin/signal	AS4C4M16S pin	STM32F429IIT6 FMC signal	STM32 GPIO	LQFP176 pin	Notes
A0	23	FMC_A0	PF0	16	Address
A1	24	FMC_A1	PF1	17	Address
A2	25	FMC_A2	PF2	18	Address
A3	26	FMC_A3	PF3	19	Address
A4	29	FMC_A4	PF4	20	Address
A5	30	FMC_A5	PF5	21	Address
A6	31	FMC_A6	PF12	60	Address
A7	32	FMC_A7	PF13	63	Address
A8	33	FMC_A8	PF14	64	Address
A9	34	FMC_A9	PF15	65	Address
A10/AP	22	FMC_A10	PG0	66	Address / auto-precharge
A11	35	FMC_A11	PG1	67	Address
BA0	20	FMC_BA0	PG4	verify in STM32 pin table	Bank address 0
BA1	21	FMC_BA1	PG5	verify in STM32 pin table	Bank address 1
DQ0	2	FMC_D0	PD14	104	Data bit 0
DQ1	4	FMC_D1	PD15	105	Data bit 1
DQ2	5	FMC_D2	PD0	142	Data bit 2
DQ3	7	FMC_D3	PD1	143	Data bit 3
DQ4	8	FMC_D4	PE7	68	Data bit 4
DQ5	10	FMC_D5	PE8	69	Data bit 5
DQ6	11	FMC_D6	PE9	70	Data bit 6
DQ7	13	FMC_D7	PE10	73	Data bit 7
DQ8	42	FMC_D8	PE11	74	Data bit 8
DQ9	44	FMC_D9	PE12	75	Data bit 9
DQ10	45	FMC_D10	PE13	76	Data bit 10
DQ11	47	FMC_D11	PE14	77	Data bit 11
DQ12	48	FMC_D12	PE15	78	Data bit 12
DQ13	50	FMC_D13	PD8	96	Data bit 13
DQ14	51	FMC_D14	PD9	97	Data bit 14
DQ15	53	FMC_D15	PD10	98	Data bit 15
LDQM	15	FMC_NBL0	PE0	169	Lower byte mask
UDQM	39	FMC_NBL1	PE1	170	Upper byte mask
CLK	38	FMC_SDCLK	PG8	112	SDRAM clock
CKE	37	FMC_SDCKE0	PH2	43	Clock enable, bank 0
CS#	19	FMC_SDNE0	PH3	44	Chip select, bank 0
RAS#	18	FMC_SDNRAS	PF11	59	Row strobe
CAS#	17	FMC_SDNCAS	PG15	160	Column strobe
WE#	16	FMC_SDNWE	PH5	46	Write enable; PC0 is alternate

Power pins

Connect all SDRAM power pins to the same I/O rail as the STM32 FMC bank, typically 3V3 unless the system is intentionally using a different supported I/O voltage.

Table

AS4C4M16S pin	Signal	Connect to
1, 14, 27	VDD	3V3
3, 9, 43, 49	VDDQ	3V3
28, 41, 54	VSS	GND
6, 12, 46, 52	VSSQ	GND

Add local decoupling: one 100 nF ceramic near each VDD/VDDQ group, plus a local bulk capacitor such as 4.7 µF-10 µF near the SDRAM. Keep VDDQ return paths tight because the DQ bus is the noisiest part of the interface.

NC / RFU pins

Table

AS4C4M16S pin	Signal	Recommendation
36	NC	Leave unconnected
40	NC/RFU	Leave unconnected unless a newer datasheet for the exact ordering code says otherwise

Pulls / series resistors

Usually do not add pull-ups to the SDRAM command/address/data bus.
If needed for signal integrity, reserve optional 0-33 ohm series resistors close to the STM32 on SDCLK first, and optionally on command/control lines. Populate values after bring-up or simulation.
Do not add RC filtering on SDRAM signals.

Layout guidance

Place the SDRAM close to the STM32 FMC pins.
Route SDCLK short and clean; consider it the timing reference.
Keep DQ0-DQ15 and DQM lines length-matched reasonably within byte lanes. For moderate SDRAM clocks on a compact board, exact DDR-style matching is not needed, but avoid large stubs and long detours.
Route over a continuous ground reference plane.
Avoid splitting the ground plane under the SDRAM bus.
Put SDRAM decoupling caps on the same side as the SDRAM where possible, immediately adjacent to VDD/VDDQ pins with direct ground vias.

Firmware / FMC configuration notes

Configure the STM32 FMC in SDRAM bank 0 with:

Memory width: 16-bit
Address bits used by the memory: A0-A11 plus BA0/BA1
Data mask enabled via NBL0/NBL1
GPIO alternate function: AF12 for FMC pins

Timing parameters must be derived from the exact AS4C4M16S speed grade and the selected FMC clock. Do not copy timings blindly from another board unless HCLK/FMC clock and SDRAM speed grade match.

Items to verify before schematic capture

Confirm the exact AS4C4M16S package pinout for AS4C4M16S-6TINTR matches the 54-pin TSOP II pinout used here.
Confirm STM32 PG4/PG5 LQFP176 package pin numbers for BA0/BA1 directly from the ST datasheet table before committing the symbol.
Confirm whether the board has competing uses for PH2, PH3, PH5. If yes, use the alternate PC3, PC2, PC0 FMC mappings instead.
Confirm voltage domain compatibility: SDRAM VDD/VDDQ must match the STM32 FMC GPIO bank voltage.

Summary
Core signal mapping
Power pins
NC / RFU pins
Pulls / series resistors
Layout guidance
Firmware / FMC configuration notes
Items to verify before schematic capture