Board definition for CH32X033F8P6 TSSOP20 #171

At the current stage it works for me. Have fun!
Info below is also in the readme of the board definition directory.

+------v------+
MISO/A6 D6~ 1-+PA6 PA5+-20 D5 SCK/A5
MOSI/A8/TX4 D7 2-+PA7=PB0 PA4+-19 D4~ CS/A4
A9/RX4 D8 3-+PB1 PC19+-18 D17 SWCLK
/RST D9 4-+PB7 PA3+-17 D3~ RX2/A3*
USBDM D10 5-+PC16=PC11 PA2+-16 D2~ TX2/A2
USBDP D11 6-+PC17=PC10 PA1+-15 D1~ A1
GND 7-+VSS PA0+-14 D0~ A0
SWDIO D16 8-+PC18 PC3+-13 D15~ A13
VCC 9-+VDD PA10+-12 D14 SCL/TX1
D12 10-+PA9 PA11+-11 D13 SDA/RX1
+-------------+
*A3, VREF and hardware I2C don't work on CH32X033F8P6 0-series (lot number with the penultimate bit 5 being 0).

 
Tested features

digitalWrite()/digitalRead() - can use Arduino pin numbers or PAx notation.
analogWrite() - 12-bit resolution, pins marked with ~ in pinout above.
analogRead() - very stable 12-bit resolution, but issues with A3/A0/PADC_VREF
Serial.print() - Tested 115200 bps on Serial2 (PA2/PA3) and Serial1 (PA10/PA11), as set in variant_CH32X033F8P6.h
EEPROM library - may need improvement (updated to support 122 bytes).
Pin PB7 (Arduino pin 9) can be configured as hardware reset /RST using WCH Link Utility. (See issue Hardware reset pin doesn't work on CH32X033 or CH32X035 #123)
Known issues/limitations

Pins PA7/PB0, PC16/PC11 and PC17/PC10 cannot be used for output.
Any signal on A0 seems to show on other ADC pins when disconnected.
A3, PADC_VREF and I2C don't work on CH32X033F8P6 0-series (lot number with the penultimate bit 5 being 0).
To counter missing I2C the Software_I2C library by Seeed Studio is a good alternative, although it needs some changes to improve compatibility in I2C scanning.

openwch/arduino_core_ch32#171

Author: jobitjoseph

libraries/EEPROM/src/EEPROM.cpp

@@ -18,10 +18,44 @@
    These 8 bytes use 16 bytes of flash. The total storage area page is 64 bytes, leaving 48 bytes available, 
    (including required inverse values). This is 24 bytes that can be used plus the two data0 and data1 bytes. 
    Layout for uint8_t _data[26]: { ob[4], ob[6], ob[16...62] ].
+   At the current stage it works for me. Have fun!
+Info below is also in the readme of the board definition directory.
+
++------v------+
+MISO/A6 D6~ 1-+PA6 PA5+-20 D5 SCK/A5
+MOSI/A8/TX4 D7 2-+PA7=PB0 PA4+-19 D4~ CS/A4
+A9/RX4 D8 3-+PB1 PC19+-18 D17 SWCLK
+/RST D9 4-+PB7 PA3+-17 D3~ RX2/A3*
+USBDM D10 5-+PC16=PC11 PA2+-16 D2~ TX2/A2
+USBDP D11 6-+PC17=PC10 PA1+-15 D1~ A1
+GND 7-+VSS PA0+-14 D0~ A0
+SWDIO D16 8-+PC18 PC3+-13 D15~ A13
+VCC 9-+VDD PA10+-12 D14 SCL/TX1
+D12 10-+PA9 PA11+-11 D13 SDA/RX1
++-------------+
+*A3, VREF and hardware I2C don't work on CH32X033F8P6 0-series (lot number with the penultimate bit 5 being 0).
+
+ 
+Tested features
+
+digitalWrite()/digitalRead() - can use Arduino pin numbers or PAx notation.
+analogWrite() - 12-bit resolution, pins marked with ~ in pinout above.
+analogRead() - very stable 12-bit resolution, but issues with A3/A0/PADC_VREF
+Serial.print() - Tested 115200 bps on Serial2 (PA2/PA3) and Serial1 (PA10/PA11), as set in variant_CH32X033F8P6.h
+EEPROM library - may need improvement (updated to support 122 bytes).
+Pin PB7 (Arduino pin 9) can be configured as hardware reset /RST using WCH Link Utility. (See issue Hardware reset pin doesn't work on CH32X033 or CH32X035 #123)
+Known issues/limitations
+
+Pins PA7/PB0, PC16/PC11 and PC17/PC10 cannot be used for output.
+Any signal on A0 seems to show on other ADC pins when disconnected.
+A3, PADC_VREF and I2C don't work on CH32X033F8P6 0-series (lot number with the penultimate bit 5 being 0).
+To counter missing I2C the Software_I2C library by Seeed Studio is a good alternative, although it needs some changes to improve compatibility in I2C scanning.
+
+https://github.com/openwch/arduino_core_ch32/pull/171
 */
 #include <EEPROM.h>
 
-#define OB_AVAIL_DATA_START 8  // valid for CH32V003; how about others?
+#define OB_AVAIL_DATA_START 8 // valid for CH32V003; how about others? (same for X03x, V20x, V30x, V31x)
 
 EEPROMClass::EEPROMClass(void) {
 }
@@ -44,7 +78,11 @@ uint32_t EEPROMClass::ReadOptionBytes()
 
 void EEPROMClass::begin(void)
 {
-  _size = 26;   // Option bytes available on CH32V003: 64 - 16 = 48; 48/2=24, 2+24=26
+  #if defined(CH32VM00X) ||  defined(CH32X035)
+    _size = 122;   // Option bytes available on CH32V002/V006, CH32X035/X033: 256- 16 = 240; 240/2=120, 2+120=122
+  #else 
+    _size = 26;   // Option bytes available on CH32V003: 64 - 16 = 48; 48/2=24, 2+24=26
+  #endif
 
   // Allocate data buffer and copy the current content from storage
   if(!_data)
@@ -141,13 +179,29 @@ bool EEPROMClass::commit()
   // Note that when a byte is written as a word, it automatically gets its inverse value as second byte
   if(_data && _size)
   {
+    #if defined(CH32VM00X) || defined(CH32X035)
+      // To write to the larger 256B option byte area of V00X, we use fast page programming as shown by EVT EXAM code
+      // (see FLASH_OptionBytePR() in /EVT/EXAM/SRC/Peripheral/src/ch32v00X_flash.c)
+      // Tested OK for V002/V006. X035 seems similar, but first needs testing 
+      FLASH_Unlock_Fast();
+      FLASH_BufReset();
+      for (int i=2;i<_size; i++) {
+        uint32_t val;
+        val=_data[i+1]<<16 | _data[i];
+        FLASH_BufLoad((OB_BASE + (OB_AVAIL_DATA_START + (i-2))*2), val);
+        i++;
+      }
+      FLASH_ProgramPage_Fast(OB_BASE);
+      FLASH_Lock_Fast();    
+    #else
     uint16_t *ob16p=(uint16_t *)OB_BASE;
     for (int i=2;i<_size; i++) {
       if(_data[i]!=0xFF) {
         ob16p[OB_AVAIL_DATA_START+(i-2)]=_data[i];
         while (FLASH->STATR & FLASH_BUSY);	// Wait for flash operation to be done
       }
     }
+    #endif
   }
 
   FLASH->CTLR &= CR_OPTPG_Reset;			// Disable programming mode
@@ -167,3 +221,4 @@ bool EEPROMClass::end() {
 #if !defined(NO_GLOBAL_INSTANCES) && !defined(NO_GLOBAL_EEPROM)
 EEPROMClass EEPROM;
 #endif
+