VoCore2: About Pin Share

Pin share or I call it pinmux, it is a common feature of most MCU chips. Normally a pin we can use it as GPIO or some special functions.

In picture, the orange number is each pins GPIO number. And in the color block, there is its special function.

Here is a table from vocore.io/v2.html, for example, the pin 29 on the chip has three functions, one is used as GPIO, one is system reference clock, final one is SDcard CLK.

+3.3VO+3.3V outputmax output current 100mA
30TXD0GPIO12, UART0 Lite TXDpull down to GND, Test/Normal mode pin.
31RXD0GPIO13, UART0 Lite RXD3.3V
29REFCLKGPIO11, reference clock, SDXC CLK*
33P0RP10/100 PHY Port #0 RXP
34P0RN10/100 PHY Port #0 RXN
35P0TP10/100 PHY Port #0 TXP
36P0TN10/100 PHY Port #0 TXN
43TXD210/100 PHY Port #1 TXN, GPIO15, PWM Channel, SPI Slave Clock
44RXD210/100 PHY Port #1 TXP, GPIO14, PWM Channel, SPI Slave Chip Select
40PWM010/100 PHY Port #1 RXN, GPIO17, UART2 Lite TXD, SPI Slave MOSI4.7K pull down to GND
42PWM110/100 PHY Port #1 RXP, GPIO16, UART2 Lite RXD, SPI Slave MISO
45P2RP10/100 PHY Port #2 RXP, GPIO18, PWM Channel
46P2RN10/100 PHY Port #2 RXN, GPIO19, PWM Channel
47P2TP10/100 PHY Port #2 TXP, GPIO20, PWM Channel
48P2TN10/100 PHY Port #2 TXN, GPIO21, PWM Channel
49SD WPGPIO22, 10/100 PHY Port #3 TXP, SDXC WP
50SD CDGPIO23, 10/100 PHY Port #3 TXN, SDXC CD
28SPI CS0SPI Master Chip Select 04.7K pull up to 3.3V
25SPI CLKSPI Master Clock4.7K pull up to 3.3V
26SPI MISOSPI Master In Slave Out
27SPI MOSISPI Master Out Slave In4.7K pull down to GND
24SPI CS1SPI Master Chip Select 14.7K pull down to GND
21I2C SDGPIO5, I2C Data, SDXC D2*4.7K pull up to 3.3V
20I2C CLKGPIO4, I2C Clock, SDXC D3*4.7K pull up to 3.3V
19I2S CLKGPIO3, I2S Bit Clock, SDXC CMD*
18I2S WSGPIO2, I2S L/R Clock, SDXC D0*
16I2S SDIGPIO0, I2S Data In, SDXC D1*
17I2S SDOGPIO1, I2S Data Out4.7K pull down to GND
147TXD1GPIO13, UART1 Lite TXDpull up to 3.3V, GPIO/JTAG mode pin
141GPIO41GPIO41, JTAG TMSJTAG needs 10K pull up, R9 -> R6
140GPIO40GPIO40, JTAG ClockJTAG needs 10K pull up, R9 -> R6
139GPIO39GPIO39, JTAG ResetJTAG needs 10K pull up, R9 -> R6
143GPIO43GPIO43, JTAG TDOJTAG needs 10K pull up, R9 -> R6
142GPIO42GPIO42, JTAG TDIJTAG needs 10K pull up, R9 -> R6
138RSTReset, touch GND to reset
+3.3VO+3.3V outputmax output current 100mA
+1.8VO+1.8V outputmax output current 100mA
51SD D1GPIO24, 10/100 PHY Port #3 RXP, SDXC D1
52SD D0GPIO25, 10/100 PHY Port #3 RXN, SDXC D0
54SD CLKGPIO26, 10/100 PHY Port #4 RXP, SDXC CLK
55SD CMDGPIO27, 10/100 PHY Port #4 RXN, SDXC CMD
56SD D3GPIO28, 10/100 PHY Port #4 TXP, SDXC D3
57SD D2GPIO29, 10/100 PHY Port #4 TXN, SDXC D2
+3.3VO+3.3V outputmax output current 100mA
61USB DPUSB2.0 Data+
62USB DMUSB2.0 Data-
+5.0VI+5.0V inputmin input current 500mA
+5.0VI+5.0V inputmin input current 500mA
133PCI CKPPCI Express External Reference Clock Output+
132PCI CKNPCI Express External Reference Clock Output-
130PCI RXNPCI Express Differential Receiver RX-
129PCI RXPPCI Express Differential Receiver RX+
127PCI TXPPCI Express Differential Transmit TX+
126PCI TXNPCI Express Differential Transmit TX-
135PCI RSTPCI Express Device Reset

On VoCore2 Ultimate, ES8388 do not need external clock because we can use VoCore2 system reference clock as its source, in most situation, that will save cost of the BOM.

Set the Pin Function

now, question come, how do we setup every pins function? Sometimes you may want use it as GPIO but sometimes we need to use as clock.

Actually it is same as other MCU(like STM32 and ATMEGA–Arduino) , we have register for every function.

Use this REFCLK pin as example, we can find on MT7628AN datasheet page 117, 2.2 System Control Section, 0x10000060 is that control register.

Its register is 1:0 two bits. (note: on this datasheet, its name is GPIO mode)

We can write 10b to this register, then it will be REFCLK mode.

and after it into REFCLK mode, we can change its frequency, at page 110, 0x1000002c register, bit 11:9 REFCLK0_RATE

And you can use same way to change other pins function 🙂

Also I have a simple tool to do this, please download at vocore.io/v2.html, Directly write to memory/register Section.