[product + cart] single product / multiple cart

now when you press a button on the cart you notify the product launchpad about your presence;
then the product launchpad always sends packets to you;
this allows the use of multiple carts with only a single product

project/Giomba/status.c

@@ -73,7 +73,7 @@ void s_shopping(process_event_t ev, process_data_t data) {
                 basket_msg m;
                 m.msg_type = BASKET_MSG;
                 m.n_products = nprod;
-                m.customer_id = customer_id;    /* TODO -- is this really needed? */
+                m.customer_id = customer_id;    /* this is needed to handle multiple customers at the cash register */
                 net_send(&m, sizeof(m), &cash_address);
                 status = CASH_OUT_WAIT4ACK;
             }
@@ -82,6 +82,12 @@ void s_shopping(process_event_t ev, process_data_t data) {
             }
         }
     }
+    if (ev == button_hal_release_event) {   /* any button will do */
+        /* ask product to send items to me */
+        msg m;
+        m.msg_type = START_SHOPPING_MSG;
+        net_send(&m, sizeof(m), NULL);
+    }
 }
 
 void s_cash_out_wait4ack(process_event_t ev, process_data_t data) {

project/Giomba/status.h

@@ -5,6 +5,8 @@
 #include "sys/etimer.h"
 #include "sys/process.h"
 
+#include "os/dev/button-hal.h"
+
 #include "../common/supermarket_net.h"
 #include "event.h"
 #include "sendrecv.h"

project/common/supermarket_net.h

@@ -15,7 +15,8 @@ enum message_type {
     PRODUCT_PARTIAL_LIST_MSG,   /* from cart to cash */
     BASKET_MSG,
     START_OF_LIST_PRODUCTS_MSG,
-    PRODUCT_PARTIAL_LIST_ACK    /* everytime the cash register receives a product message, it sends an ack to the cart so that the cart can send the next product message */
+    PRODUCT_PARTIAL_LIST_ACK,   /* everytime the cash register receives a product message, it sends an ack to the cart so that the cart can send the next product message */
+    START_SHOPPING_MSG
 };
 
 typedef struct msg {

project/product/product.c

@@ -16,8 +16,7 @@
 #define LOG_MODULE "App"
 #define LOG_LEVEL LOG_LEVEL_INFO
 
-/* Hardcoded MAC Address for cart */
+/* MAC Address for cart -- This emulates the RFID tag */
-/* This is used only to emulate the RFID tag */
 static linkaddr_t dest_addr = {{0x00, 0x12, 0x4b, 0x00, 0x0f, 0x82, 0x00, 0x04}};
 
 product_t product_list[] = {
@@ -43,12 +42,22 @@ void scan_product(product_t* p){
 	LOG_INFO_("\n");
 }
 
+void net_recv(const void* data, uint16_t len, const linkaddr_t* src, const linkaddr_t* dst) {
+    if (((msg*)data)->msg_type == START_SHOPPING_MSG) {
+        printf("Now sending products to new cart\n");
+        memcpy(&dest_addr, src, sizeof(src));
+    }
+}
+
 PROCESS_THREAD(product_proc, ev, data){
 	PROCESS_BEGIN();
 	// init random number generator
-	unsigned int magic_seed = 12; // oooh :o
+	unsigned int magic_seed = 12;
 	srand(magic_seed);
 
+    // init network subsystem
+    nullnet_set_input_callback(net_recv);
+
 	while(1) {
 		PROCESS_YIELD();
 		if (ev == button_hal_press_event){