pybricks · laurensvalk · Jul 11, 2025 · Jun 29, 2025
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -7,6 +7,9 @@
 ### Added
 - Experimental support for USB connectivity on SPIKE Prime ([pybricks-micropython#208]).
 - Initial support for `pybricks.iodevices.UARTDevice` ([support#220]). 
+- Enabled previously hidden support for multiple code
+  slots ([pybricks-micropython#264], [pybricks-micropython#312]). A new
+  (unreleased) version of Pybricks Code is needed to use this.
 
 ### Changed
 - Extensive overhaul of UART and port drivers on all hubs. This affects all
@@ -21,6 +24,8 @@
 [support#220]: https://github.com/pybricks/support/issues/220
 [support#2206]: https://github.com/pybricks/support/issues/2206
 [pybricks-micropython#208]: https://github.com/pybricks/pybricks-micropython/pull/208
+[pybricks-micropython#264]: https://github.com/pybricks/pybricks-micropython/pull/264
+[pybricks-micropython#312]: https://github.com/pybricks/pybricks-micropython/pull/312
 
 ## [3.6.1] - 2025-03-11
 

diff --git a/lib/pbio/drv/bluetooth/bluetooth_stm32_bluenrg.c b/lib/pbio/drv/bluetooth/bluetooth_stm32_bluenrg.c
@@ -1078,7 +1078,7 @@ static PT_THREAD(init_pybricks_service(struct pt *pt)) {
     PT_WAIT_WHILE(pt, write_xfer_size);
     {
         uint8_t buf[PBIO_PYBRICKS_HUB_CAPABILITIES_VALUE_SIZE];
-        pbio_pybricks_hub_capabilities(buf, ATT_MTU - 3, PBSYS_CONFIG_APP_FEATURE_FLAGS, pbsys_storage_get_maximum_program_size());
+        pbio_pybricks_hub_capabilities(buf, ATT_MTU - 3, PBSYS_CONFIG_APP_FEATURE_FLAGS, pbsys_storage_get_maximum_program_size(), 0);
         aci_gatt_update_char_value_begin(pybricks_service_handle, pybricks_hub_capabilities_char_handle,
             0, PBIO_PYBRICKS_HUB_CAPABILITIES_VALUE_SIZE, buf);
     }

diff --git a/lib/pbio/drv/bluetooth/bluetooth_stm32_cc2640.c b/lib/pbio/drv/bluetooth/bluetooth_stm32_cc2640.c
@@ -1483,7 +1483,7 @@ static void handle_event(uint8_t *packet) {
                         uint8_t buf[PBIO_PYBRICKS_HUB_CAPABILITIES_VALUE_SIZE];
 
                         // REVISIT: this assumes connection_handle == conn_handle
-                        pbio_pybricks_hub_capabilities(buf, conn_mtu - 3, PBSYS_CONFIG_APP_FEATURE_FLAGS, pbsys_storage_get_maximum_program_size());
+                        pbio_pybricks_hub_capabilities(buf, conn_mtu - 3, PBSYS_CONFIG_APP_FEATURE_FLAGS, pbsys_storage_get_maximum_program_size(), 0);
                         rsp.len = sizeof(buf);
                         rsp.pValue = buf;
                         ATT_ReadRsp(connection_handle, &rsp);

diff --git a/lib/pbio/drv/bluetooth/pybricks_service_server.c b/lib/pbio/drv/bluetooth/pybricks_service_server.c
@@ -89,7 +89,7 @@ static uint16_t pybricks_service_read_callback(hci_con_handle_t con_handle, uint
     if (attribute_handle == pybricks_hub_capabilities_value_handle) {
         if (buffer && buffer_size >= PBIO_PYBRICKS_HUB_CAPABILITIES_VALUE_SIZE) {
             pbio_pybricks_hub_capabilities(buffer, pbio_int_math_min(att_server_get_mtu(con_handle) - 3, 512),
-                PBSYS_CONFIG_APP_FEATURE_FLAGS, pbsys_storage_get_maximum_program_size());
+                PBSYS_CONFIG_APP_FEATURE_FLAGS, pbsys_storage_get_maximum_program_size(), PBSYS_CONFIG_HMI_NUM_SLOTS);
         }
         return PBIO_PYBRICKS_HUB_CAPABILITIES_VALUE_SIZE;
     }

diff --git a/lib/pbio/drv/usb/stm32_usbd/usbd_desc.c b/lib/pbio/drv/usb/stm32_usbd/usbd_desc.c
@@ -536,7 +536,8 @@ void USBD_Pybricks_Desc_Init(void) {
     pbio_pybricks_hub_capabilities(ptr,
         USBD_PYBRICKS_MAX_PACKET_SIZE - 1,
         PBSYS_CONFIG_APP_FEATURE_FLAGS,
-        pbsys_storage_get_maximum_program_size());
+        pbsys_storage_get_maximum_program_size(),
+        PBSYS_CONFIG_HMI_NUM_SLOTS);
     ptr += PBIO_PYBRICKS_HUB_CAPABILITIES_VALUE_SIZE;
 
     /* Update wTotalLength field in BOS Descriptor */

diff --git a/lib/pbio/include/pbio/protocol.h b/lib/pbio/include/pbio/protocol.h
@@ -24,7 +24,7 @@
 #define PBIO_PROTOCOL_VERSION_MAJOR 1
 
 /** The minor version number for the protocol. */
-#define PBIO_PROTOCOL_VERSION_MINOR 4
+#define PBIO_PROTOCOL_VERSION_MINOR 5
 
 /** The patch version number for the protocol. */
 #define PBIO_PROTOCOL_VERSION_PATCH 0
@@ -342,9 +342,9 @@ typedef enum {
 #define PBIO_PYBRICKS_STATUS_FLAG(status) (1 << status)
 
 /** Size of status report event message in bytes. */
-#define PBIO_PYBRICKS_EVENT_STATUS_REPORT_SIZE 6
+#define PBIO_PYBRICKS_EVENT_STATUS_REPORT_SIZE 7
 
-uint32_t pbio_pybricks_event_status_report(uint8_t *buf, uint32_t flags, pbio_pybricks_user_program_id_t program_id);
+uint32_t pbio_pybricks_event_status_report(uint8_t *buf, uint32_t flags, pbio_pybricks_user_program_id_t program_id, uint8_t slot);
 
 /**
  * Application-specific feature flag supported by a hub.
@@ -391,12 +391,13 @@ typedef enum {
 void pbio_pybricks_hub_capabilities(uint8_t *buf,
     uint16_t max_char_size,
     pbio_pybricks_feature_flags_t feature_flags,
-    uint32_t max_user_prog_size);
+    uint32_t max_user_prog_size,
+    uint8_t num_slots);
 
 /**
  * Number of bytes in the Pybricks hub capabilities characteristic value.
  */
-#define PBIO_PYBRICKS_HUB_CAPABILITIES_VALUE_SIZE 10
+#define PBIO_PYBRICKS_HUB_CAPABILITIES_VALUE_SIZE 11
 
 extern const uint8_t pbio_pybricks_service_uuid[];
 extern const uint8_t pbio_pybricks_command_event_char_uuid[];

diff --git a/lib/pbio/include/pbsys/status.h b/lib/pbio/include/pbsys/status.h
@@ -14,7 +14,7 @@
 
 #include <pbio/protocol.h>
 
-#define PBSYS_STATUS_REPORT_SIZE 6
+#define PBSYS_STATUS_REPORT_SIZE 7
 
 /**
  * Status flag change.

diff --git a/lib/pbio/platform/prime_hub/pbsysconfig.h b/lib/pbio/platform/prime_hub/pbsysconfig.h
@@ -10,7 +10,7 @@
 #define PBSYS_CONFIG_BLUETOOTH                      (1)
 #define PBSYS_CONFIG_BLUETOOTH_TOGGLE               (1)
 #define PBSYS_CONFIG_BLUETOOTH_TOGGLE_BUTTON        (512) // PBIO_BUTTON_RIGHT_UP, but enum value cannot be used here.
-#define PBSYS_CONFIG_HMI_NUM_SLOTS                  (0)
+#define PBSYS_CONFIG_HMI_NUM_SLOTS                  (5)
 #define PBSYS_CONFIG_HUB_LIGHT_MATRIX               (1)
 #define PBSYS_CONFIG_HOST                           (1)
 #define PBSYS_CONFIG_MAIN                           (1)

diff --git a/lib/pbio/platform/test/pbsysconfig.h b/lib/pbio/platform/test/pbsysconfig.h
@@ -8,6 +8,7 @@
 #define PBSYS_CONFIG_FEATURE_PROGRAM_FORMAT_MULTI_MPY_V6_1_NATIVE  (0)
 #define PBSYS_CONFIG_BLUETOOTH                      (1)
 #define PBSYS_CONFIG_HOST                           (1)
+#define PBSYS_CONFIG_HMI_NUM_SLOTS                  (0)
 #define PBSYS_CONFIG_HUB_LIGHT_MATRIX               (0)
 #define PBSYS_CONFIG_MAIN                           (0)
 #define PBSYS_CONFIG_STORAGE                        (0)

diff --git a/lib/pbio/src/protocol/pybricks.c b/lib/pbio/src/protocol/pybricks.c
@@ -17,15 +17,22 @@ _Static_assert(NUM_PBIO_PYBRICKS_STATUS <= sizeof(uint32_t) * 8,
  *
  * The buffer must be at least ::PBIO_PYBRICKS_EVENT_STATUS_REPORT_SIZE bytes.
  *
+ * @since Pybricks Profile v1.0.0
+ *
+ * Program ID parameter was added in Pybricks Profile v1.4.0.
+ * Slot parameter was added in Pybricks Profile v1.5.0.
+ *
  * @param [in]  buf         The buffer to hold the binary data.
  * @param [in]  flags       The status flags.
- * @param [in]  program_id  Program identifier.
+ * @param [in]  program_id  Program identifier of currently running program.
+ * @param [in]  slot        The currently selected program slot.
  * @return                  The number of bytes written to @p buf.
  */
-uint32_t pbio_pybricks_event_status_report(uint8_t *buf, uint32_t flags, pbio_pybricks_user_program_id_t program_id) {
+uint32_t pbio_pybricks_event_status_report(uint8_t *buf, uint32_t flags, pbio_pybricks_user_program_id_t program_id, uint8_t slot) {
     buf[0] = PBIO_PYBRICKS_EVENT_STATUS_REPORT;
     pbio_set_uint32_le(&buf[1], flags);
     buf[5] = program_id;
+    buf[6] = slot;
     return PBIO_PYBRICKS_EVENT_STATUS_REPORT_SIZE;
 }
 
@@ -37,15 +44,22 @@ uint32_t pbio_pybricks_event_status_report(uint8_t *buf, uint32_t flags, pbio_py
  * @param [in]  max_char_size       The maximum characteristic value size (negotiated MTU - 3).
  * @param [in]  feature_flags       The feature flags.
  * @param [in]  max_user_prog_size  The maximum allowable size for the user program.
+ * @param [in]  num_slots           The number of program slots available on the hub.
+ *
+ * @since Pybricks Profile v1.2.0
+ *
+ * num_slots was added in Pybricks Profile v1.5.0.
  */
 void pbio_pybricks_hub_capabilities(uint8_t *buf,
     uint16_t max_char_size,
     pbio_pybricks_feature_flags_t feature_flags,
-    uint32_t max_user_prog_size) {
+    uint32_t max_user_prog_size,
+    uint8_t num_slots) {
 
     pbio_set_uint16_le(&buf[0], max_char_size);
     pbio_set_uint32_le(&buf[2], feature_flags);
     pbio_set_uint32_le(&buf[6], max_user_prog_size);
+    buf[10] = num_slots;
 }
 
 /**

diff --git a/lib/pbio/sys/bluetooth.c b/lib/pbio/sys/bluetooth.c
@@ -22,6 +22,7 @@
 #include <pbsys/status.h>
 #include <pbsys/storage.h>
 
+#include "hmi.h"
 #include "storage.h"
 
 // REVISIT: this can be the negotiated MTU - 3 to allow for better throughput
@@ -254,6 +255,9 @@ static PT_THREAD(pbsys_bluetooth_monitor_status(struct pt *pt)) {
     static struct etimer timer;
     static uint32_t old_status_flags;
     static send_msg_t msg;
+    #if PBSYS_CONFIG_HMI_NUM_SLOTS
+    static uint8_t old_program_slot;
+    #endif
 
     PT_BEGIN(pt);
 
@@ -267,7 +271,11 @@ static PT_THREAD(pbsys_bluetooth_monitor_status(struct pt *pt)) {
 
     for (;;) {
         // wait for status to change or timeout
-        PT_WAIT_UNTIL(pt, pbsys_status_get_flags() != old_status_flags || etimer_expired(&timer));
+        PT_WAIT_UNTIL(pt, pbsys_status_get_flags() != old_status_flags ||
+            #if PBSYS_CONFIG_HMI_NUM_SLOTS
+            pbsys_hmi_get_selected_program_slot() != old_program_slot ||
+            #endif
+            etimer_expired(&timer));
 
         etimer_restart(&timer);
 

diff --git a/lib/pbio/sys/status.c b/lib/pbio/sys/status.c
@@ -59,9 +59,16 @@ static void pbsys_status_update_flag(pbio_pybricks_status_t status, bool set) {
  * @return                 The number of bytes written to @p buf.
  */
 uint32_t pbsys_status_get_status_report(uint8_t *buf) {
+    #if PBSYS_CONFIG_HMI_NUM_SLOTS
+    uint8_t slot = pbsys_hmi_get_selected_program_slot();
+    #else
+    uint8_t slot = 0;
+    #endif
+
     _Static_assert(PBSYS_STATUS_REPORT_SIZE == PBIO_PYBRICKS_EVENT_STATUS_REPORT_SIZE,
         "size of status report does not match size of event");
-    return pbio_pybricks_event_status_report(buf, pbsys_status.flags, pbsys_status.program_id);
+
+    return pbio_pybricks_event_status_report(buf, pbsys_status.flags, pbsys_status.program_id, slot);
 }
 
 /**