diff --git a/lib/pbio/drv/uart/uart_ev3.c b/lib/pbio/drv/uart/uart_ev3.c
index 5069d7636..adedc316c 100644
--- a/lib/pbio/drv/uart/uart_ev3.c
+++ b/lib/pbio/drv/uart/uart_ev3.c
@@ -62,7 +62,7 @@ struct _pbdrv_uart_dev_t {
     /** The current position in read_buf. */
     uint8_t read_pos;
     /** The buffer passed to the write function. */
-    uint8_t *write_buf;
+    const uint8_t *write_buf;
     /** The length of write_buf in bytes. */
     uint8_t write_length;
     /** The current position in write_buf. */
@@ -131,7 +131,7 @@ pbio_error_t pbdrv_uart_read(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uin
     PBIO_OS_ASYNC_END(PBIO_SUCCESS);
 }
 
-static pbio_error_t pbdrv_uart_write_pru(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uint8_t *msg, uint8_t length, uint32_t timeout) {
+static pbio_error_t pbdrv_uart_write_pru(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, const uint8_t *msg, uint8_t length, uint32_t timeout) {
 
     const pbdrv_uart_ev3_platform_data_t *pdata = uart->pdata;
 
@@ -178,7 +178,7 @@ static pbio_error_t pbdrv_uart_write_pru(pbio_os_state_t *state, pbdrv_uart_dev_
     PBIO_OS_ASYNC_END(PBIO_SUCCESS);
 }
 
-pbio_error_t pbdrv_uart_write_hw(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uint8_t *msg, uint8_t length, uint32_t timeout) {
+pbio_error_t pbdrv_uart_write_hw(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, const uint8_t *msg, uint8_t length, uint32_t timeout) {
 
     const pbdrv_uart_ev3_platform_data_t *pdata = uart->pdata;
 
@@ -240,7 +240,7 @@ pbio_error_t pbdrv_uart_write_hw(pbio_os_state_t *state, pbdrv_uart_dev_t *uart,
     PBIO_OS_ASYNC_END(PBIO_SUCCESS);
 }
 
-pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uint8_t *msg, uint8_t length, uint32_t timeout) {
+pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, const uint8_t *msg, uint8_t length, uint32_t timeout) {
     const pbdrv_uart_ev3_platform_data_t *pdata = uart->pdata;
 
     if (pdata->uart_kind == EV3_UART_HW) {
diff --git a/lib/pbio/drv/uart/uart_ev3_pru.c b/lib/pbio/drv/uart/uart_ev3_pru.c
index d3884fc2c..5b7e92f6a 100644
--- a/lib/pbio/drv/uart/uart_ev3_pru.c
+++ b/lib/pbio/drv/uart/uart_ev3_pru.c
@@ -32,6 +32,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdbool.h>
+#include <stdint.h>
 
 #include <errno.h>
 
@@ -481,7 +482,7 @@ int32_t pbdrv_uart_ev3_pru_get_break_state(uint8_t line) {
     return 0;
 }
 
-int32_t pbdrv_uart_ev3_pru_write_bytes(uint8_t line, uint8_t *pdata, int32_t size) {
+int32_t pbdrv_uart_ev3_pru_write_bytes(uint8_t line, const uint8_t *pdata, int32_t size) {
     omapl_pru_suart_t *suart = &suartdevs[line];
 
     if (suart->write_busy || size == 0) {
diff --git a/lib/pbio/drv/uart/uart_ev3_pru.h b/lib/pbio/drv/uart/uart_ev3_pru.h
index 367b22bb1..c4573d6b7 100644
--- a/lib/pbio/drv/uart/uart_ev3_pru.h
+++ b/lib/pbio/drv/uart/uart_ev3_pru.h
@@ -8,10 +8,10 @@ int pbdrv_uart_ev3_pru_load_firmware(uint8_t *firmware_data, uint32_t firmware_s
 int pbdrv_uart_ev3_pru_activate(uint8_t line);
 
 void pbdrv_uart_ev3_pru_handle_irq_data(uint8_t line);
-void pbdrv_uart_ev3_pru_set_baudrate(uint8_t line, unsigned int baud);
+void pbdrv_uart_ev3_pru_set_baudrate(uint8_t line, uint32_t baud);
 
-int pbdrv_uart_ev3_pru_read_bytes(uint8_t line, unsigned char *pdata, int size);
-int pbdrv_uart_ev3_pru_write_bytes(uint8_t line, unsigned char *pdata, int size);
+int pbdrv_uart_ev3_pru_read_bytes(uint8_t line, uint8_t *pdata, int32_t size);
+int pbdrv_uart_ev3_pru_write_bytes(uint8_t line, const uint8_t *pdata, int32_t size);
 bool pbdrv_uart_ev3_pru_can_write(uint8_t line);
 
 #endif // _INTERNAL_PBDRV_UART_EV3_PRU_H_
diff --git a/lib/pbio/drv/uart/uart_stm32f0.c b/lib/pbio/drv/uart/uart_stm32f0.c
index 98cf00236..12b9f5d80 100644
--- a/lib/pbio/drv/uart/uart_stm32f0.c
+++ b/lib/pbio/drv/uart/uart_stm32f0.c
@@ -35,7 +35,7 @@ struct _pbdrv_uart_dev_t {
     uint8_t *rx_buf;
     uint8_t rx_buf_size;
     uint8_t rx_buf_index;
-    uint8_t *tx_buf;
+    const uint8_t *tx_buf;
     uint8_t tx_buf_size;
     uint8_t tx_buf_index;
     pbio_os_timer_t rx_timer;
@@ -102,7 +102,7 @@ pbio_error_t pbdrv_uart_read(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uin
     PBIO_OS_ASYNC_END(PBIO_SUCCESS);
 }
 
-pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uint8_t *msg, uint8_t length, uint32_t timeout) {
+pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, const uint8_t *msg, uint8_t length, uint32_t timeout) {
 
     PBIO_OS_ASYNC_BEGIN(state);
 
diff --git a/lib/pbio/drv/uart/uart_stm32f4_ll_irq.c b/lib/pbio/drv/uart/uart_stm32f4_ll_irq.c
index 88fd75c69..f52720817 100644
--- a/lib/pbio/drv/uart/uart_stm32f4_ll_irq.c
+++ b/lib/pbio/drv/uart/uart_stm32f4_ll_irq.c
@@ -43,7 +43,7 @@ struct _pbdrv_uart_dev_t {
     /** The current position in read_buf. */
     uint8_t read_pos;
     /** The buffer of the ongoing write function. */
-    uint8_t *write_buf;
+    const uint8_t *write_buf;
     /** The length of write_buf in bytes. */
     uint8_t write_length;
     /** The current position in write_buf. */
@@ -108,7 +108,7 @@ pbio_error_t pbdrv_uart_read(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uin
     PBIO_OS_ASYNC_END(PBIO_SUCCESS);
 }
 
-pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uint8_t *msg, uint8_t length, uint32_t timeout) {
+pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, const uint8_t *msg, uint8_t length, uint32_t timeout) {
 
     PBIO_OS_ASYNC_BEGIN(state);
 
diff --git a/lib/pbio/drv/uart/uart_stm32l4_ll_dma.c b/lib/pbio/drv/uart/uart_stm32l4_ll_dma.c
index 74bb8c850..d9fbf4050 100644
--- a/lib/pbio/drv/uart/uart_stm32l4_ll_dma.c
+++ b/lib/pbio/drv/uart/uart_stm32l4_ll_dma.c
@@ -227,7 +227,7 @@ pbio_error_t pbdrv_uart_read(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uin
     PBIO_OS_ASYNC_END(PBIO_SUCCESS);
 }
 
-pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uint8_t *msg, uint8_t length, uint32_t timeout) {
+pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, const uint8_t *msg, uint8_t length, uint32_t timeout) {
 
     const pbdrv_uart_stm32l4_ll_dma_platform_data_t *pdata = uart->pdata;
 
diff --git a/lib/pbio/include/pbdrv/uart.h b/lib/pbio/include/pbdrv/uart.h
index 751972ffb..581bed46a 100644
--- a/lib/pbio/include/pbdrv/uart.h
+++ b/lib/pbio/include/pbdrv/uart.h
@@ -58,7 +58,7 @@ pbio_error_t pbdrv_uart_read(pbio_os_state_t *state, pbdrv_uart_dev_t *uart_dev,
  *
  * @return The error code.
  */
-pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, uint8_t *msg, uint8_t length, uint32_t timeout);
+pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart, const uint8_t *msg, uint8_t length, uint32_t timeout);
 
 #else // PBDRV_CONFIG_UART
 
diff --git a/lib/pbio/test/src/test_lump.c b/lib/pbio/test/src/test_lump.c
index 15e59060b..2b98873e5 100644
--- a/lib/pbio/test/src/test_lump.c
+++ b/lib/pbio/test/src/test_lump.c
@@ -34,7 +34,7 @@ struct _pbdrv_uart_dev_t {
     uint8_t *rx_msg;
     uint8_t rx_msg_length;
     pbio_error_t rx_msg_result;
-    uint8_t *tx_msg;
+    const uint8_t *tx_msg;
     pbio_os_timer_t tx_timer;
     uint8_t tx_msg_length;
     pbio_error_t tx_msg_result;
@@ -1134,7 +1134,7 @@ pbio_error_t pbdrv_uart_read(pbio_os_state_t *state, pbdrv_uart_dev_t *uart_dev,
     PBIO_OS_ASYNC_END(uart_dev->rx_msg_result);
 }
 
-pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart_dev, uint8_t *msg, uint8_t length, uint32_t timeout) {
+pbio_error_t pbdrv_uart_write(pbio_os_state_t *state, pbdrv_uart_dev_t *uart_dev, const uint8_t *msg, uint8_t length, uint32_t timeout) {
 
     PBIO_OS_ASYNC_BEGIN(state);