7. System configuration controller (SYSCFG)

The system configuration controller is mainly used to:

• • Remap the memory areas
• • Select the Ethernet PHY interface
• • Manage the external interrupt line connection to the GPIOs.

7.1 I/O compensation cell

By default the I/O compensation cell is not used. However when the I/O output buffer speed is configured in 50 MHz or 100 MHz mode, it is recommended to use the compensation cell for slew rate control on I/O \( t_{f(IO)out}/t_{r(IO)out} \) commutation to reduce the I/O noise on power supply.

When the compensation cell is enabled, a READY flag is set to indicate that the compensation cell is ready and can be used. The I/O compensation cell can be used only when the supply voltage ranges from 2.4 to 3.6 V.

7.2 SYSCFG registers

7.2.1 SYSCFG memory remap register (SYSCFG_MEMRMP)

This register is used for specific configurations on memory mapping:

• • 1bit is used to indicate which option bytes BOOT_ADD0 or BOOT_ADD1 defines the boot memory base address.
• • Other bits are used to swap FMC SDRAM Banks with FMC NOR/PSRAM bank

Address offset: 0x00
Reset value: 0x0000 0000

Bits 31:12 Reserved, must be kept at reset value.

Bits 11:10 SWP_FMC[1:0] : FMC memory mapping swap

Set and cleared by software. These bits are used to swap the FMC SDRAM banks and FMC NOR/PSRAM in order to enable the code execution from SDRAM Banks without modifying the default MPU attribute

00: No FMC memory mapping swapping

SDRAM bank1 and Bank2 are mapped at 0xC000 0000 and 0xD000 0000 respectively (default mapping)

NOR/RAM is accessible @ 0x60000000 (default mapping)

01: NOR/RAM and SDRAM memory mapping swapped,

SDRAM bank1 and bank2 are mapped at 0x6000 0000 and 0x7000 0000, respectively

NOR/PSRAM bank is mapped at 0xC000 0000

10: Reserved

11: Reserved

Bits 9:1 Reserved, must be kept at reset value.

Bit 0 MEM_BOOT : Memory boot mapping

This bit indicates which option bytes BOOT_ADD0 or BOOT_ADD1 defines the boot memory base address.

0: Boot memory base address is defined by BOOT_ADD0 option byte (Factory Reset value: TCM-FLASH mapped at 0x00200000).

1: Boot memory base address is defined by BOOT_ADD1 option byte (Factory Reset value: System memory mapped at 0x001 0000).

Note: Refer to section 2.3: Memory map for details about the boot memory base address selection.

7.2.2 SYSCFG peripheral mode configuration register (SYSCFG_PMC)

Address offset: 0x04

Reset value: 0x0000 0000

Bits 31:24 Reserved, must be kept at reset value.

Bit 23 MII_RMII_SEL : Ethernet PHY interface selection

Set and Cleared by software. These bits control the PHY interface for the Ethernet MAC.

0: MII interface is selected

1: RMII PHY interface is selected

Note: This configuration must be done while the MAC is under reset and before enabling the MAC clocks.

Bits 22:19 Reserved, must be kept at reset value.

Bits 18:16 ADCxDC2 :

0: No effect.

1: Refer to AN4073 on how to use this bit.

Note: These bits can be set only if the following conditions are met:

• - ADC clock higher or equal to 30 MHz.
• - Only one ADCxDC2 bit must be selected if ADC conversions do not start at the same time and the sampling times differ.
• - These bits must not be set when the ADCDC1 bit is set in PWR_CR register.

Bits 15:0 Reserved, must be kept at reset value.

7.2.3 SYSCFG external interrupt configuration register 1 (SYSCFG_EXTICR1)

Address offset: 0x08

Reset value: 0x0000 0000

Bits 31:16 Reserved, must be kept at reset value.

Bits 15:0 EXTIx[3:0] : EXTI x configuration (x = 0 to 3)

These bits are written by software to select the source input for the EXTIx external interrupt.

0000: PA[x] pin
0001: PB[x] pin
0010: PC[x] pin
0011: PD[x] pin
0100: PE[x] pin
0101: PF[x] pin
0110: PG[x] pin
0111: PH[x] pin
1000: PI[x] pin
1001: PJ[x] pin
1010: PK[x] pin

7.2.4 SYSCFG external interrupt configuration register 2 (SYSCFG_EXTICR2)

Address offset: 0x0C

Reset value: 0x0000 0000

Bits 31:16 Reserved, must be kept at reset value.

Bits 15:0 EXTIx[3:0] : EXTI x configuration (x = 4 to 7)

These bits are written by software to select the source input for the EXTIx external interrupt.

0000: PA[x] pin
0001: PB[x] pin
0010: PC[x] pin
0011: PD[x] pin
0100: PE[x] pin
0101: PF[x] pin
0110: PG[x] pin
0111: PH[x] pin
1000: PI[x] pin
1001: PJ[x] pin
1010: PK[x] pin

7.2.5 SYSCFG external interrupt configuration register 3 (SYSCFG_EXTICR3)

Address offset: 0x10

Reset value: 0x0000 0000

Bits 31:16 Reserved, must be kept at reset value.

Bits 15:0 EXTIx[3:0] : EXTI x configuration (x = 8 to 11)

These bits are written by software to select the source input for the EXTIx external interrupt.

0000: PA[x] pin
0001: PB[x] pin
0010: PC[x] pin
0011: PD[x] pin
0100: PE[x] pin
0101: PF[x] pin
0110: PG[x] pin
0111: PH[x] pin
1000: PI[x] pin
1001: PJ[x] pin
1010: PK[x] pin

Note: PK[11:8] are not used

7.2.6 SYSCFG external interrupt configuration register 4 (SYSCFG_EXTICR4)

Address offset: 0x14

Reset value: 0x0000 0000

Bits 31:16 Reserved, must be kept at reset value.

Bits 15:0 EXTIx[3:0] : EXTI x configuration (x = 12 to 15)

These bits are written by software to select the source input for the EXTIx external interrupt.

• 0000: PA[x] pin
• 0001: PB[x] pin
• 0010: PC[x] pin
• 0011: PD[x] pin
• 0100: PE[x] pin
• 0101: PF[x] pin
• 0110: PG[x] pin
• 0111: PH[x] pin
• 1001: PJ[x] pin
• 1010: PK[x] pin

Note: PK[15:12] are not used

7.2.7 Compensation cell control register (SYSCFG_CMPCR)

Address offset: 0x20

Reset value: 0x0000 0000

Bits 31:9 Reserved, must be kept at reset value.

Bit 8 READY : Compensation cell ready flag

• 0: I/O compensation cell not ready
• 1: O compensation cell ready

Bits 7:2 Reserved, must be kept at reset value.

Bit 0 CMP_PD : Compensation cell power-down

• 0: I/O compensation cell power-down mode
• 1: I/O compensation cell enabled

7.2.8 SYSCFG register maps

The following table gives the SYSCFG register map and the reset values.

Table 24. SYSCFG register map and reset values

Refer to Section 2.2 on page 69 for the register boundary addresses.