[Controller] Added board config for custom controller STeMCell (#16287)

Co-authored-by: Mariappan Ramasamy <947300+Mariappan@users.noreply.github.com>
Co-authored-by: Mariappan Ramasamy <maari@basis-ai.com>
Co-authored-by: Sadek Baroudi <sadekbaroudi@gmail.com>

11 files changed, 411 insertions, 1 deletions

diff --git a/builddefs/common_features.mk b/builddefs/common_features.mk
index a23b5e82b9..3d416773f7 100644
--- a/builddefs/common_features.mk
+++ b/builddefs/common_features.mk
@@ -212,7 +212,7 @@ else
     ifeq ($(PLATFORM),AVR)
       # Automatically provided by avr-libc, nothing required
     else ifeq ($(PLATFORM),CHIBIOS)
-      ifneq ($(filter STM32F3xx_% STM32F1xx_% %_STM32F401xC %_STM32F401xE %_STM32F405xG %_STM32F411xE %_STM32F072xB %_STM32F042x6 %_GD32VF103xB %_GD32VF103x8, $(MCU_SERIES)_$(MCU_LDSCRIPT)),)
+      ifneq ($(filter STM32F3xx_% STM32F1xx_% STM32F4xx_% %_STM32F401xC %_STM32F401xE %_STM32F405xG %_STM32F411xE %_STM32F072xB %_STM32F042x6 %_GD32VF103xB %_GD32VF103x8, $(MCU_SERIES)_$(MCU_LDSCRIPT)),)
         # Emulated EEPROM
         OPT_DEFS += -DEEPROM_DRIVER -DEEPROM_STM32_FLASH_EMULATED
         COMMON_VPATH += $(PLATFORM_PATH)/$(PLATFORM_KEY)/$(DRIVER_DIR)/flash
diff --git a/data/mappings/defaults.json b/data/mappings/defaults.json
index 5e25405c37..2c9fb317c9 100644
--- a/data/mappings/defaults.json
+++ b/data/mappings/defaults.json
@@ -54,6 +54,12 @@
             "processor": "STM32F411",
             "bootloader": "stm32-dfu",
             "board": "BLACKPILL_STM32_F411"
+        },
+        "stemcell": {
+            "processor": "STM32F411",
+            "bootloader": "tinyuf2",
+            "board": "STEMCELL",
+            "pin_compatible": "promicro"
         }
     }
 }
diff --git a/docs/feature_converters.md b/docs/feature_converters.md
index 569cf0f17d..936ab44559 100644
--- a/docs/feature_converters.md
+++ b/docs/feature_converters.md
@@ -15,6 +15,7 @@ Currently the following converters are available:
 | `promicro` | `promicro_rp2040` |
 | `promicro` | `blok`            |
 | `promicro` | `bit_c_pro`       |
+| `promicro` | `stemcell`        |
 
 See below for more in depth information on each converter.
 
@@ -56,6 +57,7 @@ If a board currently supported in QMK uses a [Pro Micro](https://www.sparkfun.co
 | [SparkFun Pro Micro - RP2040](https://www.sparkfun.com/products/18288) | `promicro_rp2040` |
 | [Blok](https://boardsource.xyz/store/628b95b494dfa308a6581622)         | `blok`            |
 | [Bit-C PRO](https://nullbits.co/bit-c-pro)                             | `bit_c_pro`       |
+| [STeMCell](https://github.com/megamind4089/STeMCell)                   | `stemcell`        |
 
 Converter summary:
 
@@ -66,6 +68,7 @@ Converter summary:
 | `promicro_rp2040` | `-e CONVERT_TO=promicro_rp2040` | `CONVERT_TO=promicro_rp2040` | `#ifdef CONVERT_TO_PROMICRO_RP2040` |
 | `blok`            | `-e CONVERT_TO=blok`            | `CONVERT_TO=blok`            | `#ifdef CONVERT_TO_BLOK`            |
 | `bit_c_pro`       | `-e CONVERT_TO=bit_c_pro`       | `CONVERT_TO=bit_c_pro`       | `#ifdef CONVERT_TO_BIT_C_PRO`       |
+| `stemcell`        | `-e CONVERT_TO=stemcell`        | `CONVERT_TO=stemcell`        | `#ifdef CONVERT_TO_STEMCELL`        |
 
 ### Proton C :id=proton_c
 
@@ -99,3 +102,22 @@ The following defaults are based on what has been implemented for [RP2040](platf
 ### SparkFun Pro Micro - RP2040, Blok, and Bit-C PRO :id=promicro_rp2040 
 
 Currently identical to  [Adafruit KB2040](#kb2040).
+
+### STeMCell :id=stemcell
+
+Feature set currently identical to [Proton C](#proton_c).
+There are two versions of STeMCell available, with different pinouts:
+  - v1.0.0
+  - v2.0.0 (pre-release v1.0.1, v1.0.2)
+Default official firmware only supports v2.0.0 STeMCell.
+
+STeMCell has support to swap UART and I2C pins, to enable single-wire uart communication in STM chips.
+
+The following additional flags has to be used while compiling, based on the pin used for split communication.
+
+| Split Pin | Compile flags |
+|-----------|---------------|
+| D3        | -e STMC_US=yes|
+| D2        | Not needed    |
+| D1        | -e STMC_IS=yes|
+| D0        | Not needed    |
diff --git a/platforms/chibios/boards/STEMCELL/board/board.mk b/platforms/chibios/boards/STEMCELL/board/board.mk
new file mode 100644
index 0000000000..b0d1c3c404
--- /dev/null
+++ b/platforms/chibios/boards/STEMCELL/board/board.mk
@@ -0,0 +1,15 @@
+# Copyright 2022 Mega Mind (@megamind4089)
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+# Default pin config of nucleo64_411re has most pins in input pull up mode
+
+# List of all the board related files.
+BOARDSRC = $(CHIBIOS)/os/hal/boards/ST_NUCLEO64_F411RE/board.c
+
+# Required include directories
+BOARDINC = $(CHIBIOS)/os/hal/boards/ST_NUCLEO64_F411RE
+
+
+# Shared variables
+ALLCSRC += $(BOARDSRC)
+ALLINC  += $(BOARDINC)
diff --git a/platforms/chibios/boards/STEMCELL/configs/board.h b/platforms/chibios/boards/STEMCELL/configs/board.h
new file mode 100644
index 0000000000..39cf79ab09
--- /dev/null
+++ b/platforms/chibios/boards/STEMCELL/configs/board.h
@@ -0,0 +1,8 @@
+// Copyright 2022 Mega Mind (@megamind4089)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include_next "board.h"
+
+#undef STM32_HSE_BYPASS
diff --git a/platforms/chibios/boards/STEMCELL/configs/chconf.h b/platforms/chibios/boards/STEMCELL/configs/chconf.h
new file mode 100644
index 0000000000..d25bea0d17
--- /dev/null
+++ b/platforms/chibios/boards/STEMCELL/configs/chconf.h
@@ -0,0 +1,9 @@
+// Copyright 2022 Mega Mind (@megamind4089)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#define CH_CFG_ST_RESOLUTION 16
+#define CH_CFG_ST_FREQUENCY 10000
+
+#include_next <chconf.h>
diff --git a/platforms/chibios/boards/STEMCELL/configs/config.h b/platforms/chibios/boards/STEMCELL/configs/config.h
new file mode 100644
index 0000000000..82f6c63636
--- /dev/null
+++ b/platforms/chibios/boards/STEMCELL/configs/config.h
@@ -0,0 +1,29 @@
+// Copyright 2022 Mega Mind(@megamind4089)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#ifndef EARLY_INIT_PERFORM_BOOTLOADER_JUMP
+#    define EARLY_INIT_PERFORM_BOOTLOADER_JUMP TRUE
+#endif
+
+/**======================
+ **    I2C Driver
+ *========================**/
+
+#if !defined(I2C1_SDA_PIN)
+#    define I2C1_SDA_PIN D0
+#endif
+
+#if !defined(I2C1_SCL_PIN)
+#    define I2C1_SCL_PIN D1
+#endif
+
+/**======================
+ **      SERIAL Driver
+ *========================**/
+
+#if !defined(SERIAL_USART_DRIVER)
+#    define SERIAL_USART_DRIVER SD2
+#endif
+
diff --git a/platforms/chibios/boards/STEMCELL/configs/halconf.h b/platforms/chibios/boards/STEMCELL/configs/halconf.h
new file mode 100644
index 0000000000..f38949e626
--- /dev/null
+++ b/platforms/chibios/boards/STEMCELL/configs/halconf.h
@@ -0,0 +1,11 @@
+// Copyright 2022 Mega Mind (@megamind4089)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#define PAL_USE_WAIT TRUE
+#define PAL_USE_CALLBACKS TRUE
+#define HAL_USE_I2C TRUE
+#define HAL_USE_SERIAL TRUE
+
+#include_next <halconf.h>
diff --git a/platforms/chibios/boards/STEMCELL/configs/mcuconf.h b/platforms/chibios/boards/STEMCELL/configs/mcuconf.h
new file mode 100644
index 0000000000..621d3fcace
--- /dev/null
+++ b/platforms/chibios/boards/STEMCELL/configs/mcuconf.h
@@ -0,0 +1,231 @@
+// Copyright 2022 Mega Mind (@megamind4089)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#ifndef MCUCONF_H
+#define MCUCONF_H
+
+/*
+ * STM32F4xx drivers configuration.
+ * The following settings override the default settings present in
+ * the various device driver implementation headers.
+ * Note that the settings for each driver only have effect if the whole
+ * driver is enabled in halconf.h.
+ *
+ * IRQ priorities:
+ * 15...0       Lowest...Highest.
+ *
+ * DMA priorities:
+ * 0...3        Lowest...Highest.
+ */
+
+#define STM32F4xx_MCUCONF
+#define STM32F411_MCUCONF
+
+/*
+ * HAL driver system settings.
+ */
+#define STM32_NO_INIT                       FALSE
+#define STM32_PVD_ENABLE                    FALSE
+#define STM32_PLS                           STM32_PLS_LEV0
+#define STM32_BKPRAM_ENABLE                 FALSE
+#define STM32_HSI_ENABLED                   TRUE
+#define STM32_LSI_ENABLED                   TRUE
+#define STM32_HSE_ENABLED                   TRUE
+#define STM32_LSE_ENABLED                   FALSE
+#define STM32_CLOCK48_REQUIRED              TRUE
+#define STM32_SW                            STM32_SW_PLL
+#define STM32_PLLSRC                        STM32_PLLSRC_HSE
+#define STM32_PLLM_VALUE                    8
+#define STM32_PLLN_VALUE                    336
+#define STM32_PLLP_VALUE                    4
+#define STM32_PLLQ_VALUE                    7
+#define STM32_HPRE                          STM32_HPRE_DIV1
+#define STM32_PPRE1                         STM32_PPRE1_DIV2
+#define STM32_PPRE2                         STM32_PPRE2_DIV1
+#define STM32_RTCSEL                        STM32_RTCSEL_LSI
+#define STM32_RTCPRE_VALUE                  8
+#define STM32_MCO1SEL                       STM32_MCO1SEL_HSI
+#define STM32_MCO1PRE                       STM32_MCO1PRE_DIV1
+#define STM32_MCO2SEL                       STM32_MCO2SEL_SYSCLK
+#define STM32_MCO2PRE                       STM32_MCO2PRE_DIV5
+#define STM32_I2SSRC                        STM32_I2SSRC_CKIN
+#define STM32_PLLI2SN_VALUE                 192
+#define STM32_PLLI2SR_VALUE                 5
+
+/*
+ * IRQ system settings.
+ */
+#define STM32_IRQ_EXTI0_PRIORITY            6
+#define STM32_IRQ_EXTI1_PRIORITY            6
+#define STM32_IRQ_EXTI2_PRIORITY            6
+#define STM32_IRQ_EXTI3_PRIORITY            6
+#define STM32_IRQ_EXTI4_PRIORITY            6
+#define STM32_IRQ_EXTI5_9_PRIORITY          6
+#define STM32_IRQ_EXTI10_15_PRIORITY        6
+#define STM32_IRQ_EXTI16_PRIORITY           6
+#define STM32_IRQ_EXTI17_PRIORITY           15
+#define STM32_IRQ_EXTI18_PRIORITY           6
+#define STM32_IRQ_EXTI19_PRIORITY           6
+#define STM32_IRQ_EXTI20_PRIORITY           6
+#define STM32_IRQ_EXTI21_PRIORITY           15
+#define STM32_IRQ_EXTI22_PRIORITY           15
+
+#define STM32_IRQ_TIM1_BRK_TIM9_PRIORITY    7
+#define STM32_IRQ_TIM1_UP_TIM10_PRIORITY    7
+#define STM32_IRQ_TIM1_TRGCO_TIM11_PRIORITY 7
+#define STM32_IRQ_TIM1_CC_PRIORITY          7
+#define STM32_IRQ_TIM2_PRIORITY             7
+#define STM32_IRQ_TIM3_PRIORITY             7
+#define STM32_IRQ_TIM4_PRIORITY             7
+#define STM32_IRQ_TIM5_PRIORITY             7
+
+#define STM32_IRQ_USART1_PRIORITY           12
+#define STM32_IRQ_USART2_PRIORITY           12
+#define STM32_IRQ_USART6_PRIORITY           12
+
+/*
+ * ADC driver system settings.
+ */
+#define STM32_ADC_ADCPRE                    ADC_CCR_ADCPRE_DIV4
+#define STM32_ADC_USE_ADC1                  FALSE
+#define STM32_ADC_ADC1_DMA_STREAM           STM32_DMA_STREAM_ID(2, 4)
+#define STM32_ADC_ADC1_DMA_PRIORITY         2
+#define STM32_ADC_IRQ_PRIORITY              6
+#define STM32_ADC_ADC1_DMA_IRQ_PRIORITY     6
+
+/*
+ * GPT driver system settings.
+ */
+#define STM32_GPT_USE_TIM1                  FALSE
+#define STM32_GPT_USE_TIM2                  FALSE
+#define STM32_GPT_USE_TIM3                  FALSE
+#define STM32_GPT_USE_TIM4                  FALSE
+#define STM32_GPT_USE_TIM5                  FALSE
+#define STM32_GPT_USE_TIM9                  FALSE
+#define STM32_GPT_USE_TIM10                 FALSE
+#define STM32_GPT_USE_TIM11                 FALSE
+
+/*
+ * I2C driver system settings.
+ */
+#define STM32_I2C_USE_I2C1                  TRUE
+#define STM32_I2C_USE_I2C2                  FALSE
+#define STM32_I2C_USE_I2C3                  FALSE
+#define STM32_I2C_BUSY_TIMEOUT              50
+#define STM32_I2C_I2C1_RX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 0)
+#define STM32_I2C_I2C1_TX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 6)
+#define STM32_I2C_I2C2_RX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 2)
+#define STM32_I2C_I2C2_TX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 7)
+#define STM32_I2C_I2C3_RX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 2)
+#define STM32_I2C_I2C3_TX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 4)
+#define STM32_I2C_I2C1_IRQ_PRIORITY         5
+#define STM32_I2C_I2C2_IRQ_PRIORITY         5
+#define STM32_I2C_I2C3_IRQ_PRIORITY         5
+#define STM32_I2C_I2C1_DMA_PRIORITY         3
+#define STM32_I2C_I2C2_DMA_PRIORITY         3
+#define STM32_I2C_I2C3_DMA_PRIORITY         3
+#define STM32_I2C_DMA_ERROR_HOOK(i2cp)      osalSysHalt("DMA failure")
+
+/*
+ * I2S driver system settings.
+ */
+#define STM32_I2S_USE_SPI2                  FALSE
+#define STM32_I2S_USE_SPI3                  FALSE
+#define STM32_I2S_SPI2_IRQ_PRIORITY         10
+#define STM32_I2S_SPI3_IRQ_PRIORITY         10
+#define STM32_I2S_SPI2_DMA_PRIORITY         1
+#define STM32_I2S_SPI3_DMA_PRIORITY         1
+#define STM32_I2S_SPI2_RX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 3)
+#define STM32_I2S_SPI2_TX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 4)
+#define STM32_I2S_SPI3_RX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 0)
+#define STM32_I2S_SPI3_TX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 7)
+#define STM32_I2S_DMA_ERROR_HOOK(i2sp)      osalSysHalt("DMA failure")
+
+/*
+ * ICU driver system settings.
+ */
+#define STM32_ICU_USE_TIM1                  FALSE
+#define STM32_ICU_USE_TIM2                  FALSE
+#define STM32_ICU_USE_TIM3                  FALSE
+#define STM32_ICU_USE_TIM4                  FALSE
+#define STM32_ICU_USE_TIM5                  FALSE
+#define STM32_ICU_USE_TIM9                  FALSE
+#define STM32_ICU_USE_TIM10                 FALSE
+#define STM32_ICU_USE_TIM11                 FALSE
+
+/*
+ * PWM driver system settings.
+ */
+#define STM32_PWM_USE_TIM1                  FALSE
+#define STM32_PWM_USE_TIM2                  FALSE
+#define STM32_PWM_USE_TIM3                  FALSE
+#define STM32_PWM_USE_TIM4                  FALSE
+#define STM32_PWM_USE_TIM5                  FALSE
+#define STM32_PWM_USE_TIM9                  FALSE
+#define STM32_PWM_USE_TIM10                 FALSE
+#define STM32_PWM_USE_TIM11                 FALSE
+
+/*
+ * SERIAL driver system settings.
+ */
+#define STM32_SERIAL_USE_USART1             TRUE
+#define STM32_SERIAL_USE_USART2             TRUE
+#define STM32_SERIAL_USE_USART6             FALSE
+
+/*
+ * SPI driver system settings.
+ */
+#define STM32_SPI_USE_SPI1                  FALSE
+#define STM32_SPI_USE_SPI2                  FALSE
+#define STM32_SPI_USE_SPI3                  FALSE
+#define STM32_SPI_SPI1_RX_DMA_STREAM        STM32_DMA_STREAM_ID(2, 0)
+#define STM32_SPI_SPI1_TX_DMA_STREAM        STM32_DMA_STREAM_ID(2, 3)
+#define STM32_SPI_SPI2_RX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 3)
+#define STM32_SPI_SPI2_TX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 4)
+#define STM32_SPI_SPI3_RX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 0)
+#define STM32_SPI_SPI3_TX_DMA_STREAM        STM32_DMA_STREAM_ID(1, 7)
+#define STM32_SPI_SPI1_DMA_PRIORITY         1
+#define STM32_SPI_SPI2_DMA_PRIORITY         1
+#define STM32_SPI_SPI3_DMA_PRIORITY         1
+#define STM32_SPI_SPI1_IRQ_PRIORITY         10
+#define STM32_SPI_SPI2_IRQ_PRIORITY         10
+#define STM32_SPI_SPI3_IRQ_PRIORITY         10
+#define STM32_SPI_DMA_ERROR_HOOK(spip)      osalSysHalt("DMA failure")
+
+/*
+ * ST driver system settings.
+ */
+#define STM32_ST_IRQ_PRIORITY               8
+#define STM32_ST_USE_TIMER                  2
+
+/*
+ * UART driver system settings.
+ */
+#define STM32_UART_USE_USART1               FALSE
+#define STM32_UART_USE_USART2               FALSE
+#define STM32_UART_USE_USART6               FALSE
+#define STM32_UART_USART1_RX_DMA_STREAM     STM32_DMA_STREAM_ID(2, 5)
+#define STM32_UART_USART1_TX_DMA_STREAM     STM32_DMA_STREAM_ID(2, 7)
+#define STM32_UART_USART2_RX_DMA_STREAM     STM32_DMA_STREAM_ID(1, 5)
+#define STM32_UART_USART2_TX_DMA_STREAM     STM32_DMA_STREAM_ID(1, 6)
+#define STM32_UART_USART6_RX_DMA_STREAM     STM32_DMA_STREAM_ID(2, 2)
+#define STM32_UART_USART6_TX_DMA_STREAM     STM32_DMA_STREAM_ID(2, 7)
+#define STM32_UART_USART1_DMA_PRIORITY      0
+#define STM32_UART_USART2_DMA_PRIORITY      0
+#define STM32_UART_USART6_DMA_PRIORITY      0
+#define STM32_UART_DMA_ERROR_HOOK(uartp)    osalSysHalt("DMA failure")
+
+/*
+ * USB driver system settings.
+ */
+#define STM32_USB_USE_OTG1                  TRUE
+#define STM32_USB_OTG1_IRQ_PRIORITY         14
+#define STM32_USB_OTG1_RX_FIFO_SIZE         512
+#define STM32_USB_HOST_WAKEUP_DURATION      2
+
+/*
+ * WDG driver system settings.
+ */
+#define STM32_WDG_USE_IWDG                  FALSE
+
+#endif /* MCUCONF_H */
diff --git a/platforms/chibios/converters/promicro_to_stemcell/_pin_defs.h b/platforms/chibios/converters/promicro_to_stemcell/_pin_defs.h
new file mode 100644
index 0000000000..f5dd55905d
--- /dev/null
+++ b/platforms/chibios/converters/promicro_to_stemcell/_pin_defs.h
@@ -0,0 +1,57 @@
+// Copyright 2022 Mega Mind (@megamind4089)
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+// Pindefs for v2.0.0
+// https://megamind4089.github.io/STeMCell/pinout/
+
+// Left side (front)
+#ifdef STEMCELL_UART_SWAP
+#    define D3 PAL_LINE(GPIOA, 3)
+#    define D2 PAL_LINE(GPIOA, 2)
+#else
+#    define D3 PAL_LINE(GPIOA, 2)
+#    define D2 PAL_LINE(GPIOA, 3)
+#endif
+//      GND
+//      GND
+#ifdef STEMCELL_I2C_SWAP
+#    define D1 PAL_LINE(GPIOB, 6)
+#    define D0 PAL_LINE(GPIOB, 7)
+#else
+#    define D1 PAL_LINE(GPIOB, 7)
+#    define D0 PAL_LINE(GPIOB, 6)
+#endif
+
+#define D4 PAL_LINE(GPIOA, 15)
+#define C6 PAL_LINE(GPIOB, 3)
+#define D7 PAL_LINE(GPIOB, 4)
+#define E6 PAL_LINE(GPIOB, 5)
+#define B4 PAL_LINE(GPIOB, 8)
+#define B5 PAL_LINE(GPIOB, 9)
+
+// Right side (front)
+//      RAW
+//      GND
+//      RESET
+//      VCC
+#define F4 PAL_LINE(GPIOB, 10)
+#define F5 PAL_LINE(GPIOB, 2)
+#define F6 PAL_LINE(GPIOB, 1)
+#define F7 PAL_LINE(GPIOB, 0)
+
+#define B1 PAL_LINE(GPIOA, 5)
+#define B3 PAL_LINE(GPIOA, 6)
+#define B2 PAL_LINE(GPIOA, 7)
+#define B6 PAL_LINE(GPIOA, 4)
+
+// Extra elite-c compatible pinout
+#define B7 PAL_LINE(GPIOC, 13)
+#define D5 PAL_LINE(GPIOC, 14)
+#define C7 PAL_LINE(GPIOC, 15)
+#define F1 PAL_LINE(GPIOA, 0)
+#define F0 PAL_LINE(GPIOA, 1)
+
+// TX/RX pins of promicro
+#define B0 PAL_LINE(GPIOA, 9) // unconnected pin
diff --git a/platforms/chibios/converters/promicro_to_stemcell/converter.mk b/platforms/chibios/converters/promicro_to_stemcell/converter.mk
new file mode 100644
index 0000000000..525492f96c
--- /dev/null
+++ b/platforms/chibios/converters/promicro_to_stemcell/converter.mk
@@ -0,0 +1,22 @@
+# Copyright 2022 Mega Mind (@megamind4089)
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+MCU := STM32F411
+BOARD := STEMCELL
+BOOTLOADER := tinyuf2
+
+SERIAL_DRIVER ?= usart
+WS2812_DRIVER ?= bitbang
+
+EEPROM_DRIVER = wear_leveling
+WEAR_LEVELING_DRIVER = legacy
+
+
+ifeq ($(strip $(STMC_US)), yes)
+  OPT_DEFS += -DSTEMCELL_UART_SWAP
+endif
+
+ifeq ($(strip $(STMC_IS)), yes)
+  OPT_DEFS += -DSTEMCELL_I2C_SWAP
+endif
+