raspberrypi-pico: First release of raspberry pi pico driver code

[libsigrok.git] / src / hardware / raspberrypi-pico / api.c

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2022 Shawn Walker <ac0bi00@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
//debug print levels are err/warn/info/dbg/spew
#include <config.h>
#include <fcntl.h>
#include <glib.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <libsigrok/libsigrok.h>
#include "libsigrok-internal.h"
#include "protocol.h"


#define SERIALCOMM "115200/8n1"

static const uint32_t scanopts[] = {
        SR_CONF_CONN,  //Required OS name for the port, i.e. /dev/ttyACM0
        SR_CONF_SERIALCOMM, //Optional config of the port, i.e. 115200/8n1
};

//PulseView reads a sample rate config list as a min, max and step.
//If step is 1 then it creates a 1,2,5,10 set of selects, as well as the max.
//If step is not 1, then it gives a place to enter any value, which gives the greatest flexibility
static const uint64_t samplerates[] = {
        SR_HZ(10),
        SR_MHZ(120),
        SR_HZ(2),
};

static const uint32_t drvopts[] = {
        SR_CONF_OSCILLOSCOPE,
        SR_CONF_LOGIC_ANALYZER,
};
//SW trigger requires this
static const int32_t trigger_matches[] = {
        SR_TRIGGER_ZERO,
        SR_TRIGGER_ONE,
        SR_TRIGGER_RISING,
        SR_TRIGGER_FALLING,
        SR_TRIGGER_EDGE,
};


static const uint32_t devopts[] = {
//CLI prefers LIMIT_SAMPLES to be a list of high,low
        SR_CONF_LIMIT_SAMPLES | SR_CONF_GET | SR_CONF_SET | SR_CONF_LIST,
        SR_CONF_TRIGGER_MATCH | SR_CONF_LIST,
        SR_CONF_CAPTURE_RATIO | SR_CONF_GET | SR_CONF_SET,
//pulseview needs a list return to allow sample rate setting
        SR_CONF_SAMPLERATE | SR_CONF_GET | SR_CONF_SET | SR_CONF_LIST,
};

static struct sr_dev_driver raspberrypi_pico_driver_info;


static GSList *scan(struct sr_dev_driver *di, GSList *options)
{
        struct sr_config *src;
        struct sr_dev_inst *sdi;
        struct sr_serial_dev_inst *serial;
        struct dev_context *devc;
        struct sr_channel *ch;
        GSList *l;
        int num_read;
        unsigned int i;
        const char *conn, *serialcomm;
        char buf[32];
        int len;
        uint8_t num_a,num_d,a_size;
        gchar *channel_name;
 
        conn = serialcomm = NULL;
        for (l = options; l; l = l->next) {
                src = l->data;
                switch (src->key) {
                case SR_CONF_CONN:
                        conn = g_variant_get_string(src->data, NULL);
                        break;
                case SR_CONF_SERIALCOMM:
                        serialcomm = g_variant_get_string(src->data, NULL);
                        break;
                }
        }
        if (!conn)
                return NULL;

        if (!serialcomm)
                serialcomm = SERIALCOMM;

        serial = sr_serial_dev_inst_new(conn, serialcomm);
        sr_info("Opening %s.", conn);
        if (serial_open(serial, SERIAL_RDWR) != SR_OK){
                sr_err("1st serial open fail");
                return NULL;
        }

        sr_info("Reseting device with *s at %s.", conn);
        send_serial_char(serial,'*');
        g_usleep(10000);
        //drain any inflight data
        do{
           sr_warn("Drain reads");
           len=serial_read_blocking(serial, buf,32,100);
           sr_warn("Drain reads done");
           if(len) sr_dbg("Dropping in flight serial data");
        }while(len>0);


        //Send identify 
        num_read=send_serial_w_resp(serial,"i\n",buf,17);
        if(num_read<16){
          sr_err("1st identify failed");
          serial_close(serial);
          g_usleep(100000);
          if (serial_open(serial, SERIAL_RDWR) != SR_OK){
                sr_err("2st serial open fail");
                return NULL;
          }
          g_usleep(100000);
          sr_err("Send second *");
          send_serial_char(serial,'*');
          g_usleep(100000);
          num_read=send_serial_w_resp(serial,"i\n",buf,17);
          if(num_read<10){
            sr_err("Second attempt failed");
            return NULL;
          }
        }
        //Expected ID response is SRPICO,AxxyDzz,VV 
        //where xx are number of analog channels, y is bytes per analog sample
        //and zz is number of digital channels, and VV is two digit version# which must be 00
        if((num_read<16)
           ||(strncmp(buf,"SRPICO,A",8))
           ||(buf[11]!='D')
           ||(buf[15]!='0') 
           ||(buf[16]!='0')){
           sr_err("ERROR:Bad response string %s %d",buf,num_read);
           return NULL;
        }
        a_size=buf[10]-'0';
        buf[10]='\0'; //Null to end the str for atois
        buf[14]='\0'; //Null to end the str for atois
        num_a=atoi(&buf[8]);
        num_d=atoi(&buf[12]);

        sdi = g_malloc0(sizeof(struct sr_dev_inst));
        sdi->status = SR_ST_INACTIVE;
        sdi->vendor = g_strdup("Raspberry Pi");
        sdi->model = g_strdup("PICO");
        sdi->version = g_strdup("00");
        sdi->conn = serial;
        sdi->driver = &raspberrypi_pico_driver_info;
        sdi->inst_type = SR_INST_SERIAL;
        sdi->serial_num = g_strdup("N/A");
        if(((num_a==0)&&(num_d==0))
           ||(num_a>MAX_ANALOG_CHANNELS)
           ||(num_d>MAX_DIGITAL_CHANNELS)
           ||(a_size<1)
           ||(a_size>4)){
                sr_err("ERROR: invalid channel config a %d d %d asz %d",num_a,num_d,a_size);
                return NULL;
        }
        devc = g_malloc0(sizeof(struct dev_context));
        devc->a_size=a_size;
        //multiple bytes per analog sample not supported
        if((num_a>0)&&(devc->a_size!=1)){
          sr_err("Only Analog Size of 1 supported\n\r");
          return NULL;
        }
        devc->num_a_channels=num_a;
        devc->num_d_channels=num_d;
        devc->a_chan_mask=((1<<num_a)-1);
        devc->d_chan_mask=((1<<num_d)-1);
//The number of bytes that each digital sample in the buffers sent to the session. 
//All logical channels are packed together, where a slice of N channels takes roundup(N/8) bytes
//This never changes even if channels are disabled because PV expects disabled channels to still 
//be accounted for in the packing
        devc->dig_sample_bytes=((devc->num_d_channels+7)/8);
        //These are the slice sizes of the data on the wire
        //1 7 bit field per byte
        devc->bytes_per_slice=(devc->num_a_channels*devc->a_size);
        if(devc->num_d_channels>0){
            // logic sent in groups of 7
          devc->bytes_per_slice+=(devc->num_d_channels+6)/7;
        }
        sr_dbg("num channels a %d d %d bps %d dsb %d",num_a,num_d,devc->bytes_per_slice,devc->dig_sample_bytes);
//Each analog channel is it's own group
//Digital are just channels
//Grouping of channels is rather arbitrary as parameters like sample rate and number of samples
//apply to all changes.  Analog channels do have a scale and offset, but that is applied
//without involvement of the session.
        devc->analog_groups = g_malloc0(sizeof(struct sr_channel_group *) *
                devc->num_a_channels);
        for (i = 0; i < devc->num_a_channels; i++) {
                channel_name = g_strdup_printf("A%d", i );
                                    //sdi, index, type, enabled,name
                ch = sr_channel_new(sdi, i, SR_CHANNEL_ANALOG, TRUE, channel_name);
                devc->analog_groups[i] = g_malloc0(sizeof(struct sr_channel_group));
                devc->analog_groups[i]->name = channel_name;
                devc->analog_groups[i]->channels = g_slist_append(NULL, ch);
                sdi->channel_groups = g_slist_append(sdi->channel_groups,
                        devc->analog_groups[i]);
        }

        if (devc->num_d_channels>0) {
                for (i = 0; i < devc->num_d_channels; i++){
                        //Name digital channels starting at D2 to match pico board pin names
                        channel_name = g_strdup_printf("D%d", i+2);
                        sr_channel_new(sdi, i, SR_CHANNEL_LOGIC, TRUE,
                                       channel_name);
                        g_free(channel_name);
                }

        }
        //In large sample usages we get the call to receive with large transfers.
        //Since the CDC serial implemenation can silenty lose data as it gets close to full, allocate
        //storage for a half buffer which in a worst case scenario has 2x ratio of transmitted bytes
        // to storage bytes. 
        //Note: The intent of making this buffer large is to prevent CDC serial buffer overflows.
        //However, it is likely that if the host is running slow (i.e. it's a raspberry pi model 3) that it becomes
        //compute bound and doesn't service CDC serial responses in time to not overflow the internal CDC buffers.
        //And thus no serial buffer is large enough.  But, it's only 256K....
        devc->serial_buffer_size=256000;
        devc->buffer=NULL;
        sr_dbg("Setting serial buffer size: %i.", devc->serial_buffer_size);
        devc->cbuf_wrptr=0;
        //While slices are sent as a group of one sample across all channels, sigrok wants analog 
        //channel data sent as separate packets.  
        //Logical trace values are packed together.
        //A serial byte in normal mode never represent more than one sample so a 2x multiplier is plenty.
        //In D4 mode a serial byte can represents 100s of samples due to RLE, but process_D4 ensures that
        //it breaks up the rle_memset calls to prevent overflowing the sample buffer.
        //that it doesn't overflow the sample buffers.
        devc->sample_buf_size=devc->serial_buffer_size*2;
        for(i=0;i<devc->num_a_channels;i++){
            devc->a_data_bufs[i]=NULL;
            devc->a_pretrig_bufs[i]=NULL;
        }
        devc->d_data_buf=NULL;
        devc->sample_rate=5000;        
        devc->capture_ratio=10;
        devc->rxstate=RX_IDLE;
        sdi->priv = devc;
        //Set an initial value as various code relies on an inital value.
        devc->limit_samples=1000;

        if(raspberrypi_pico_get_dev_cfg(sdi)!=SR_OK){
            return NULL;
        };
   
        sr_err("sr_err level logging enabled");
        sr_warn("sr_warn level logging enabled");
        sr_info("sr_info level logging enabled");
        sr_dbg("sr_dbg level logging enabled");
        sr_spew("sr_spew level logging enabled");

        return std_scan_complete(di, g_slist_append(NULL, sdi));

}



//Note that on the initial driver load we pull all values into local storage.
//Thus gets can return local data, but sets have to issue commands to device.
static int config_set(uint32_t key, GVariant *data,
        const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
{
        struct dev_context *devc;
        int ret;
        (void)cg;
        if (!sdi)
                return SR_ERR_ARG;
        devc=sdi->priv;
        ret = SR_OK;
        sr_dbg("Got config_set key %d \n",key);
        switch (key) {
        case SR_CONF_SAMPLERATE:
                devc->sample_rate = g_variant_get_uint64(data);
                sr_dbg("config_set sr %llu\n",devc->sample_rate);
                break;
        case SR_CONF_LIMIT_SAMPLES:
                devc->limit_samples = g_variant_get_uint64(data);
                sr_dbg("config_set slimit %lld\n",devc->limit_samples);
                break;
        case SR_CONF_CAPTURE_RATIO:
                devc->capture_ratio = g_variant_get_uint64(data);
                break;

        default:
                sr_err("ERROR:config_set undefine %d\n",key);
                ret = SR_ERR_NA;
        }

        return ret;
}

static int config_get(uint32_t key, GVariant **data,
        const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
{
        struct dev_context *devc;
        sr_dbg("at config_get key %d",key);
        (void)cg;
        if (!sdi)
                return SR_ERR_ARG;

        devc = sdi->priv;
        switch (key) {
        case SR_CONF_SAMPLERATE:
                *data = g_variant_new_uint64(devc->sample_rate);
                sr_spew("sample rate get of %lld",devc->sample_rate);
                break;
        case SR_CONF_CAPTURE_RATIO:
                if (!sdi)
                        return SR_ERR;
                devc = sdi->priv;
                *data = g_variant_new_uint64(devc->capture_ratio);
                break;
        case SR_CONF_LIMIT_SAMPLES:
                sr_spew("config_get limit_samples of %llu",devc->limit_samples);
                *data = g_variant_new_uint64(devc->limit_samples);
                break;
        default:
                sr_spew("unsupported cfg_get key %d",key);
                return SR_ERR_NA;
        }
        return SR_OK;
}

static int config_list(uint32_t key, GVariant **data,
        const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
{
        (void)cg;
        //scan or device options are the only ones that can be called without a defined instance
        if((key==SR_CONF_SCAN_OPTIONS)||(key==SR_CONF_DEVICE_OPTIONS)){
            return STD_CONFIG_LIST(key, data, sdi, cg, scanopts, drvopts, devopts);
        }
        if (!sdi){
            sr_err("ERROR:\n\r\n\r\n\r Call to config list with null sdi\n\r\n\r");
            return SR_ERR_ARG;
       }
        sr_dbg("start config_list with key %X\n",key);
        switch(key){
//Pulseview in  pulseview/pv/toolbars/mainbar.cpp requires list support for frequencies as a triple
//of min,max,step.  If step is 1, then it proves a 1,2,5,10 select, but if not 1 it allows a spin box
        case SR_CONF_SAMPLERATE:
                sr_dbg("Return sample rate list");
                *data = std_gvar_samplerates_steps(ARRAY_AND_SIZE(samplerates));
                break;
//This must be set to get SW trigger support
        case SR_CONF_TRIGGER_MATCH:
                *data = std_gvar_array_i32(ARRAY_AND_SIZE(trigger_matches));
                break;
        case SR_CONF_LIMIT_SAMPLES:
                //Really this limit is up to the memory capacity of the host,
                //and users that pick huge values deserve what they get.
                //But setting this limit to prevent really crazy things.
                *data = std_gvar_tuple_u64(1LL,1000000000LL);
                sr_dbg("sr_config_list limit samples ");
                break;
        default:
               sr_dbg("reached default statement of config_list");

                return SR_ERR_NA;
        }

        return SR_OK;
}

static int dev_acquisition_start(const struct sr_dev_inst *sdi)
{
        struct sr_serial_dev_inst *serial;
        struct dev_context *devc;
        struct sr_channel *ch;
        struct sr_trigger *trigger;
        char tmpstr[20];
        GSList *l;
        int a_enabled=0,d_enabled=0,len;
        serial = sdi->conn;
        int i;
        devc = sdi->priv;
        sr_dbg("Enter acq start");
        sr_dbg("dsbstart %d",devc->dig_sample_bytes);
        devc->buffer = g_malloc(devc->serial_buffer_size);
        if(!(devc->buffer)){sr_err("ERROR:serial buffer malloc fail");return SR_ERR_MALLOC;}
        //Get device in idle state
        if(serial_drain(serial)!=SR_OK){sr_err("Initial Drain Failed\n\r");return SR_ERR;}
        send_serial_char(serial,'*');
        if(serial_drain(serial)!=SR_OK){sr_err("Second Drain Failed\n\r");return SR_ERR;}
 
        for (l = sdi->channels; l; l = l->next) {
         ch = l->data;
         sr_dbg("c %d enabled %d name %s\n",ch->index,ch->enabled,ch->name);

         if(ch->name[0]=='A'){
           devc->a_chan_mask&=~(1<<ch->index);
           if(ch->enabled) {
               devc->a_chan_mask|=(ch->enabled<<ch->index);
               a_enabled++;
           }
//           sr_dbg("A%d en %d mask 0x%X",ch->index,ch->enabled,devc->a_chan_mask);
          
         }
         if(ch->name[0]=='D'){
           devc->d_chan_mask&=~(1<<ch->index);
           if(ch->enabled) {
              devc->d_chan_mask|=(ch->enabled<<ch->index);
              d_enabled++;
  //            sr_dbg("D%d en %d mask 0x%X",ch->index,ch->enabled,devc->d_chan_mask);
           } 
         }
         sr_info("Channel enable masks D 0x%X A 0x%X",devc->d_chan_mask,devc->a_chan_mask);
         sprintf(tmpstr,"%c%d%d\n",ch->name[0],ch->enabled,ch->index);
         if (send_serial_w_ack(serial,tmpstr) != SR_OK){
            sr_err("ERROR:Channel enable fail");
            return SR_ERR;
            } else{
            
               }
       }//for all channels
         //ensure data channels are continuous
       int invalid=0;
       for(i=0;i<32;i++){
         if((devc->d_chan_mask>>i)&1){
           if(invalid){
              sr_err("Digital channel mask 0x%X not continous\n\r",devc->d_chan_mask);
              return SR_ERR;
           }
         } 
         else{
           invalid=1;
         }
       }
       //recalculate bytes_per_slice.  
       devc->bytes_per_slice=(a_enabled*devc->a_size);

       for(i=0;i<devc->num_d_channels;i+=7){
        if(((devc->d_chan_mask)>>i)&(0x7F)){(devc->bytes_per_slice)++;}
       }
       if((a_enabled==0)&&(d_enabled==0)){
         sr_err("ERROR:No channels enabled");
         return SR_ERR;
       }
       sr_dbg("bps %d\n",devc->bytes_per_slice);

       //Apply sample rate limits
       //Save off the lower rate values which are hacked way of getting configs to the device
       uint8_t cfg_bits;
       cfg_bits=(devc->sample_rate%10&0x6); //Only bits 2&1 are used as cfg_bits
       devc->sample_rate-=cfg_bits;
       sr_warn("Capture device cfg_bits of 0x%X from sample rate %lld",cfg_bits,devc->sample_rate);
       if((a_enabled==3)&&(devc->sample_rate>166660)){
         sr_err("ERROR:3 channel ADC sample rate dropped to 166.660khz");
         devc->sample_rate=166660;
       }
       if((a_enabled==2)&&(devc->sample_rate>250000)){
         sr_err("ERROR:2 channel ADC sample rate dropped to 250khz");
         devc->sample_rate=250000;
       }
       if((a_enabled==1)&&(devc->sample_rate>500000)){
         sr_err("ERROR:1 channel ADC sample rate dropped to 500khz");
         devc->sample_rate=500000;
       }
       //Depending on channel configs, rates below 5ksps are possible
       //but such a low rate can easily stream and this eliminates a lot
       //of special cases.
       if(devc->sample_rate<5000){
         sr_err("Sample rate override to min of 5ksps");
         devc->sample_rate=5000;
       }
       if(devc->sample_rate>120000000){
         sr_err("Sample rate override to max of 120Msps");
         devc->sample_rate=12000000;
       }
       //It may take a very large number of samples to notice, but if digital and analog are enabled
       //and either PIO or ADC are fractional the samples will skew over time.
       //24Mhz is the max common divisor to the 120Mhz and 48Mhz ADC clock
       //so force an integer divisor to it.
       if((a_enabled>0)&&(d_enabled>0)){
         if(24000000ULL%(devc->sample_rate)){
            uint32_t commondivint=24000000ULL/(devc->sample_rate);
            //Always increment the divisor so that we go down in frequency to avoid max sample rate issues
            commondivint++;
            devc->sample_rate=24000000ULL/commondivint;
            //While the common divisor is an integer, that does not mean the resulting sample rate is, and
            //we want to keep the sample_rate divisible by 10 to support the cfg_bits
            while((devc->sample_rate%10)&&(commondivint<4800)){
               commondivint++;
               devc->sample_rate=24000000ULL/commondivint;
               //sr_err(" sample rate of %llu div %u\n\r",devc->sample_rate,commondivint); 
              }
            //Make sure the divisor increement didn't make use go too low.
            if(devc->sample_rate<5000){devc->sample_rate=50000;}
            sr_err("WARN: Forcing common integer divisor sample rate of %llu div %u\n\r",devc->sample_rate,commondivint);
          }
          
       }   
       //If we are only digital only or only analog print a warning that the 
       //fractional divisors aren't a true PLL fractional feedback loop and thus
       //could have sample to sample variation.
       if(a_enabled>0){
         if(48000000ULL%(devc->sample_rate*a_enabled)){
           sr_warn("WARN: Non integer ADC divisor of 48Mhz clock for sample rate %llu may cause sample to sample variability.",devc->sample_rate);
          }
       }   
       if(d_enabled>0){
         if(120000000ULL%(devc->sample_rate)){
           sr_warn("WARN: Non integer PIO divisor of 120Mhz for sample rate %llu may cause sample to sample variability.",devc->sample_rate);
          }
       }   


       //modulo 10 to add cfg_bits back in
       //All code above should create overrides that are multiples of 10, but add a check just in case.
       if(devc->sample_rate%10){
         sr_err("Output sample rate %llu not mod 10",devc->sample_rate);
         devc->sample_rate=(devc->sample_rate/10)*10;
       }

       devc->sample_rate+=cfg_bits;
       if(cfg_bits){
         sr_warn("Embedding cfg_bits of 0x%X in sample_rate %lld\n\r",cfg_bits,devc->sample_rate);
       }
       sprintf(&tmpstr[0],"R%llu\n", devc->sample_rate);
       if(send_serial_w_ack(serial, tmpstr)!=SR_OK) {
           sr_err("Sample rate to device failed");
           return SR_ERR;
       }
       sprintf(tmpstr,"L%lld\n", devc->limit_samples);
       if(send_serial_w_ack(serial, tmpstr)!=SR_OK) {
           sr_err("Sample limit to device failed");
           return SR_ERR;
       }


       devc->sent_samples=0;
       devc->byte_cnt=0;
       devc->bytes_avail=0;
       devc->wrptr=0; 
       devc->cbuf_wrptr=0;
       len=serial_read_blocking(serial, devc->buffer, devc->serial_buffer_size,serial_timeout(serial, 4));
       if(len>0){
          sr_info("Pre-ARM drain had %d characters:",len);
          devc->buffer[len]=0;
          sr_info("%s",devc->buffer);
       } 

        for(i=0;i<devc->num_a_channels;i++){
           devc->a_data_bufs[i]=g_malloc(devc->sample_buf_size*sizeof(float));
           if(!(devc->a_data_bufs[i])){sr_err("ERROR:analog buffer malloc fail");return SR_ERR_MALLOC;}
        }
        if(devc->num_d_channels>0){
          devc->d_data_buf=g_malloc(devc->sample_buf_size*devc->dig_sample_bytes);
          if(!(devc->d_data_buf)){sr_err("ERROR:logic buffer malloc fail");return SR_ERR_MALLOC;}
        }

       if ((trigger = sr_session_trigger_get(sdi->session))) {
              devc->pretrig_entries = (devc->capture_ratio * devc->limit_samples) / 100;
              devc->stl = soft_trigger_logic_new(sdi, trigger, devc->pretrig_entries);
              if (!devc->stl)
                   return SR_ERR_MALLOC;
              devc->trigger_fired=FALSE;
              if(devc->pretrig_entries>0){
                  sr_dbg("Allocating pretrig buffers size %d",devc->pretrig_entries);
                  for(i=0;i<devc->num_a_channels;i++){
                      if((devc->a_chan_mask>>i)&1){
                         devc->a_pretrig_bufs[i] = g_malloc0(sizeof(float)*devc->pretrig_entries);
                         if(!devc->a_pretrig_bufs[i]){
                            sr_err("ERROR:Analog pretrigger buffer malloc failure, disabling");
                            devc->trigger_fired=TRUE;
                         }
                      }//if chan_mask
                   }//for num_a_channels
              }//if pre_trigger
              sr_info("Entering sw triggered mode");
              //post the receive before starting the device to ensure we are ready to receive data ASAP
              serial_source_add(sdi->session, serial, G_IO_IN, 200,raspberrypi_pico_receive, (void *) sdi);
              sprintf(tmpstr,"C\n");
                if(send_serial_str(serial, tmpstr) != SR_OK)
                  return SR_ERR;

        } else{
              devc->trigger_fired=TRUE;
              devc->pretrig_entries=0;
              sr_info("Entering fixed sample mode");
              serial_source_add(sdi->session, serial, G_IO_IN, 200,raspberrypi_pico_receive, (void *) sdi);
              sprintf(tmpstr,"F\n");
                if(send_serial_str(serial,tmpstr) != SR_OK)
                  return SR_ERR;
        }
        std_session_send_df_header(sdi);

        sr_dbg("dsbstartend %d",devc->dig_sample_bytes);

        if(devc->trigger_fired) std_session_send_df_trigger(sdi);
        //Keep this at the end as we don't want to be RX_ACTIVE unless everything is ok
        devc->rxstate=RX_ACTIVE;

        return SR_OK;
}
//This function is called either by the protocol code if we reached all of the samples 
//or an error condition, and also by the user clicking stop in pulseview.
//It must always be called for any acquistion that was started to free memory.
static int dev_acquisition_stop(struct sr_dev_inst *sdi)
{
        struct dev_context *devc;
        struct sr_serial_dev_inst *serial;
        sr_dbg("****at dev_acquisition_stop");
        int len;
        devc = sdi->priv;
        serial = sdi->conn;

        std_session_send_df_end(sdi);
        //If we reached this while still active it is likely because the stop button was pushed 
        //in pulseview.
        //That is generally some kind of error condition, so we don't try to check the bytenct
        if(devc->rxstate==RX_ACTIVE){
          sr_err("Reached dev_acquisition_stop in RX_ACTIVE");
        }
        if(devc->rxstate!=RX_IDLE){
          sr_err("Sending plus to stop device stream\n\r");
          send_serial_char(serial,'+'); 
        }
        //In case we get calls to receive force it to exit
        devc->rxstate=RX_IDLE;
        //drain data from device so that it doesn't confuse subsequent commands
        do{
           len=serial_read_blocking(serial, devc->buffer, devc->serial_buffer_size,100);
           if(len) sr_err("Dropping %d device bytes\n\r",len);
        }while(len>0);



        if(devc->buffer){g_free(devc->buffer);devc->buffer=NULL;}

        for(int i=0;i<devc->num_a_channels;i++){
           if(devc->a_data_bufs[i]){
              g_free(devc->a_data_bufs[i]);
              devc->a_data_bufs[i]=NULL;
           }
        }

        if(devc->d_data_buf){g_free(devc->d_data_buf);devc->d_data_buf=NULL;}
        for(int i=0;i<devc->num_a_channels;i++){
          if(devc->a_pretrig_bufs[i]) g_free(devc->a_pretrig_bufs[i]);
          devc->a_pretrig_bufs[i]=NULL;
        }

        serial= sdi->conn;
        serial_source_remove(sdi->session, serial);

        return SR_OK;
}

static struct sr_dev_driver raspberrypi_pico_driver_info = {
        .name = "raspberrypi-pico",
        .longname = "RaspberryPI PICO",
        .api_version = 1,
        .init = std_init,
        .cleanup = std_cleanup,
        .scan = scan,
        .dev_list = std_dev_list,
        .dev_clear = std_dev_clear,
        .config_get = config_get,
        .config_set = config_set,
        .config_list = config_list,
        .dev_open = std_serial_dev_open,
        .dev_close = std_serial_dev_close,
        .dev_acquisition_start = dev_acquisition_start,
        .dev_acquisition_stop = dev_acquisition_stop,
        .context = NULL,
};
SR_REGISTER_DEV_DRIVER(raspberrypi_pico_driver_info);