git diff
diff --git a/src/hal/drivers/mesa-hostmot2/hostmot2.c b/src/hal/drivers/mesa-hostmot2/hostmot2.c
index db155f4..e9c724f 100644
--- a/src/hal/drivers/mesa-hostmot2/hostmot2.c
+++ b/src/hal/drivers/mesa-hostmot2/hostmot2.c
@@ -804,6 +804,18 @@ int hm2_md_is_consistent(
 static int hm2_parse_module_descriptors(hostmot2_t *hm2) {
     int md_index, md_accepted;

+    hm2->dpll_module_present = 0;
+    for (md_index = 0; md_index < hm2->num_mds; md_index ++) {
+        hm2_module_descriptor_t *md = &hm2->md[md_index];
+
+        if (md->gtag == HM2_GTAG_HM2DPLL) {
+            hm2->dpll_module_present = 1;
+            break;
+        } else if (md->gtag == 0) {
+            break;
+        }
+    }
+
     // Run through once looking for IO Ports in case other modules
     // need them
     for (md_index = 0; md_index < hm2->num_mds; md_index ++) {
diff --git a/src/hal/drivers/mesa-hostmot2/hostmot2.h b/src/hal/drivers/mesa-hostmot2/hostmot2.h
index 81cd41a..6f118e3 100644
--- a/src/hal/drivers/mesa-hostmot2/hostmot2.h
+++ b/src/hal/drivers/mesa-hostmot2/hostmot2.h
@@ -717,6 +717,13 @@ typedef struct {
 } hm2_stepgen_instance_t;


+// these hal params affect all encoder instances
+typedef struct {
+    struct {
+        hal_s32_t *dpll_timer_num;
+    } pin;
+} hm2_stepgen_module_global_t;
+
 typedef struct {
     int num_instances;
     hm2_stepgen_instance_t *instance;
@@ -724,6 +731,10 @@ typedef struct {
     rtapi_u32 clock_frequency;
     rtapi_u8 version;

+    // module-global HAL objects...
+    hm2_stepgen_module_global_t *hal;
+    rtapi_u32 written_dpll_timer_num;
+
     // write this (via TRAM) every hm2_<foo>.write
     rtapi_u32 step_rate_addr;
     rtapi_u32 *step_rate_reg;
@@ -752,6 +763,8 @@ typedef struct {
     rtapi_u32 table_sequence_length_addr;

     rtapi_u32 master_dds_addr;
+
+    rtapi_u32 dpll_timer_num_addr;
 } hm2_stepgen_t;

 //
@@ -991,6 +1004,7 @@ typedef struct {
     hm2_module_descriptor_t md[HM2_MAX_MODULE_DESCRIPTORS];
     int num_mds;

+    int dpll_module_present;
     int use_serial_numbers;

     hm2_pin_t *pin;
diff --git a/src/hal/drivers/mesa-hostmot2/stepgen.c b/src/hal/drivers/mesa-hostmot2/stepgen.c
index a119b8b..0d48879 100644
--- a/src/hal/drivers/mesa-hostmot2/stepgen.c
+++ b/src/hal/drivers/mesa-hostmot2/stepgen.c
@@ -384,6 +384,20 @@ static void hm2_stepgen_update_mode(hostmot2_t *hm2, int i) {
 }


+static void hm2_stepgen_set_dpll_timer(hostmot2_t *hm2) {
+    rtapi_u32 data = 0;
+
+    if ((*hm2->stepgen.hal->pin.dpll_timer_num < -1) || (*hm2->stepgen.hal->pin.dpll_timer_num > 4)) {
+        *hm2->stepgen.hal->pin.dpll_timer_num = 0;
+    }
+    if (*hm2->stepgen.hal->pin.dpll_timer_num > -1) {
+        data = (*hm2->stepgen.hal->pin.dpll_timer_num << 12) | (1 << 15);
+    }
+    hm2->llio->write(hm2->llio, hm2->stepgen.dpll_timer_num_addr, &data, sizeof(rtapi_u32));
+    hm2->stepgen.written_dpll_timer_num = *hm2->stepgen.hal->pin.dpll_timer_num;
+}
+
+
 void hm2_stepgen_write(hostmot2_t *hm2) {
     int i;

@@ -418,6 +432,11 @@ void hm2_stepgen_write(hostmot2_t *hm2) {
             hm2->llio->write(hm2->llio, hm2->stepgen.mode_addr + (i * sizeof(rtapi_u32)), &hm2->stepgen.mode_reg[i], sizeof(rtapi_u32));
         }
     }
+    if (hm2->dpll_module_present) {
+        if (*hm2->stepgen.hal->pin.dpll_timer_num != hm2->stepgen.written_dpll_timer_num) {
+            hm2_stepgen_set_dpll_timer(hm2);
+        }
+    }
 }


@@ -502,6 +521,12 @@ static void hm2_stepgen_force_write_master_dds(hostmot2_t *hm2) {
     );
 }

+static void hm2_stepgen_force_write_dpll_timer(hostmot2_t *hm2) {
+    if (hm2->dpll_module_present) {
+        hm2_stepgen_set_dpll_timer(hm2);
+    }
+}
+

 void hm2_stepgen_force_write(hostmot2_t *hm2) {
     if (hm2->stepgen.num_instances == 0) return;
@@ -511,6 +536,7 @@ void hm2_stepgen_force_write(hostmot2_t *hm2) {
     hm2_stepgen_force_write_pulse_width_time(hm2);
     hm2_stepgen_force_write_pulse_idle_width(hm2);
     hm2_stepgen_force_write_master_dds(hm2);
+    hm2_stepgen_force_write_dpll_timer(hm2);
 }


@@ -612,6 +638,14 @@ int hm2_stepgen_parse_md(hostmot2_t *hm2, int md_index) {
     }


+    // allocate the module-global HAL shared memory
+    hm2->stepgen.hal = (hm2_stepgen_module_global_t *)hal_malloc(sizeof(hm2_stepgen_module_global_t));
+    if (hm2->stepgen.hal == NULL) {
+        HM2_ERR("out of memory!\n");
+        r = -ENOMEM;
+        goto fail0;
+    }
+
     hm2->stepgen.instance = (hm2_stepgen_instance_t *)hal_malloc(hm2->stepgen.num_instances * sizeof(hm2_stepgen_instance_t));
     if (hm2->stepgen.instance == NULL) {
         HM2_ERR("out of memory!\n");
@@ -632,6 +666,7 @@ int hm2_stepgen_parse_md(hostmot2_t *hm2, int md_index) {
     hm2->stepgen.table_sequence_data_setup_addr = md->base_address + (7 * md->register_stride);
     hm2->stepgen.table_sequence_length_addr = md->base_address + (8 * md->register_stride);
     hm2->stepgen.master_dds_addr = md->base_address + (9 * md->register_stride);
+    hm2->stepgen.dpll_timer_num_addr = md->base_address + (10 * md->register_stride);

     r = hm2_register_tram_write_region(hm2, hm2->stepgen.step_rate_addr, (hm2->stepgen.num_instances * sizeof(rtapi_u32)), &hm2->stepgen.step_rate_r
     if (r < 0) {
@@ -686,6 +721,16 @@ int hm2_stepgen_parse_md(hostmot2_t *hm2, int md_index) {
     {
         int i;
         char name[HAL_NAME_LEN + 1];
+
+        if (hm2->dpll_module_present) {
+            rtapi_snprintf(name, sizeof(name), "%s.stepgen.timer-number", hm2->llio->name);
+            r = hal_pin_s32_new(name, HAL_IN, &(hm2->stepgen.hal->pin.dpll_timer_num), hm2->llio->comp_id);
+            if (r < 0) {
+                HM2_ERR("error adding timer number param, aborting\n");
+                return -EINVAL;
+            }
+        }
+
         for (i = 0; i < hm2->stepgen.num_instances; i ++) {

             // Work out if table setup registers are needed.
(END)